During the five days preceding the experimental session, the participants were required to sleep at least seven hours per night (23:00/24:00–7:00/9:00) and their sleep was monitored via actigraphy. On the morning of the experimental session, the participants completed a 4-stimulus visual oddball task combining facial and nonfacial stimuli, and repeated it after 25 h of sustained wakefulness. At baseline, both study groups had poorer performance in response to facial rather than non-facial target stimuli on all indices of the oddball task, with no differences between the groups. Following sleep deprivation, rates of omission errors, commission errors and reaction time variability increased significantly in the ADHD group but not in the control group. Time and target type (face/non-face) did not have an interactive effect on any indices of the oddball task. Young adults with ADHD are more sensitive to the negative effects of sleep deprivation on attentional processes, including those related to the processing of emotional facial expressions. As poor sleep and excessive daytime sleepiness are common in individuals with ADHD, it is feasible that poor sleep quality and quantity play an important role in cognitive functioning deficits, including the processing of emotional facial expressions that are associated with ADHD.The ability to recognize emotions from facial expressions is essential to the development of complex social cognition behaviors, and impairments in this ability are associated with poor social competence. This study aimed to examine the effects of sleep deprivation on the processing of emotional facial expressions and nonfacial stimuli in young adults with and without attention-deficit/hyperactivity disorder (ADHD). Thirty-five men (mean age 25.4) with ( In particular, ADHD is associated with deficits in appraisal of others’ emotional state, including difficulties in recognition and labeling of facial expressions of emotion7.Attention-deficit/hyperactivity disorder (ADHD) is a common neuropsychiatric disorder that includes symptoms of impulsivity, hyperactivity, and inattention. In addition to the well-documented cognitive impairments of ADHD, such as difficulties with attention, reward response, and executive functioning, children and adults with ADHD demonstrate social, interpersonal, and emotional difficulties9, and impairments in this ability are associated with poor social competence1. Individuals with ADHD appear to have particular difficulty in recognizing negative emotions such as fear and anger11, and disrupted response inhibition toward facial anger cues12.The ability to recognize emotions from facial expressions is essential to the development of complex social cognition behaviors14, according to which subjects have to maintain vigilance and respond to an infrequent deviant stimulus  among a series of standard stimuli . Failures to respond to the target ("omission errors"), slow reaction time to the target (RT), and high variability of reaction time to the target (RT standard deviation [RTSD]) reflect failures in vigilance (sustained attention), while responses to the non-target (commission errors) reflect failure in response inhibition15. The oddball paradigm is also used to investigate the special role of emotional content in perception and attention16, by employing, for example, neutral facial expressions as the standard stimuli  and emotional facial expressions as the deviant stimuli . Using such a paradigm, Raz and Dan17 demonstrated that participants with ADHD generally perform worse than controls, as reflected in higher rates of omission errors and commission errors, slower RTs, and higher RTSD. However, higher rates of omissions and slower RTs in the ADHD participants compared with controls were only found in response to face targets but not in response to geometric shape targets, suggesting a specific ADHD-related deficit in the processing of emotional facial expressions.Processes related to major aspects of attention and cognitive functioning can be measured using the visual oddball paradigm19, which may contribute to their difficulties in vigilance, response inhibition, and other aspects of attention and in their ability to process emotional facial expressions. Lending support to this possibility, sleep deprivation tends to have a negative effect on sustained attention22 and on the ability to identify emotional expressions25. Moreover, studies have demonstrated that sleep difficulties aggravate impulsivity and inattentiveness in children and adults with ADHD27. In controlled studies, sleep restriction or deprivation has been shown to negatively affect attentional capabilities of children20 and adults with and without ADHD22. However, it is currently unknown whether sleep deprivation affects the attentional process involved in the detection of, and response to, emotional facial expressions in general, and among adults with ADHD in particular.ADHD is also associated with a greater risk of sleep difficulties. Specifically, 25–50% of children and adults with ADHD experience problems initiating and maintaining sleepThus, the current study aimed to compare the effects of sleep deprivation on the processing of facial expressions and nonfacial stimuli (geometric shapes) between young adults with and without ADHD using the visual oddball paradigm. The oddball task required the participants to face two frequent standard stimuli , and two deviant “target” stimuli (an angry face or geometric shape with a cross in it) that had to be detected as quickly as possible. Based on the previous findings, we hypothesized that performance in the oddball task would deteriorate following sleep deprivation, as reflected in higher omission and commission error rates, slower RTs, and higher RTSD compared to baseline. We expected that this deterioration would be more pronounced in the ADHD group and in response to facial targets. Our second hypothesis was that, prior to sleep deprivation, participants with ADHD would perform worse than controls on the oddball task in general and in response to face targets in particular.28.Nineteen male adults with ADHD  and 16 male adults without ADHD  took part in the study. Seven participants from each study group were college students, recruited via ads placed on campus. The rest of the participants were recruited from the local community using the snowball sampling technique. Only men were recruited to the study in order to reduce variability, given that women's menstrual cycle may influence sleep, alertness, and, thus, cognitive functions related to these factors29; (2) a prior diagnosis of adult ADHD by a psychiatrist or by a neurologist; and (3) meeting ADHD criteria on the modified adult version of the ADHD module in the Diagnostic Interview Schedule for Children (DISC)30.Eligibility criteria for inclusion to the ADHD study group were: (1) six or more symptoms on both the hyperactivity-impulsivity and inattention scales on the ADHD assessment questionnaire (see below)Eligibility criteria for inclusion to the control study group were: (1) at most three symptoms on each of the hyperactivity-impulsivity and inattention scales on the ADHD Rating Scale-IV; (2) no previous ADHD diagnosis and (3) failure to meet ADHD criteria on the modified adult version of the DISC ADHD module.31 and by interviews; (3) night shift employment; and (4) psychopathology as diagnosed using the Symptom Checklist-90. The reason for the last exclusion criterion was twofold: first, an attempt to isolate the effects of ADHD on the studied measures, and second, an awareness that a 25-h sleep deprivation is a stressful situation which may have a significant negative impact on individuals with serious psychiatric disorders.Exclusion criteria for both study groups were: (1) use of centrally active medications (except ADHD medications); (2) diagnosis of periodic limb movements in sleep, obstructive sleep apnea, or restless legs syndrome, screened for by using the Mini Sleep Questionnaire32). Participants who smoked (N = 9) were mostly light to moderate smokers, smoking 10 cigarettes or less per day on average.The vision of all participants was normal or corrected-to-normal. Among the participants diagnosed with ADHD, the mean age of diagnosis was 16.5 (SD = 7.94), with 64.29% diagnosed prior to the age of 18. Four of the ADHD participants were regular users of stimulant ADHD medications and the remaining participants of this group reported the sporadic use of such medications. All ADHD participants agreed not to use these medications from 24 h before the start of the experiment until its end  was necessary, assuming a medium effect size (0.06) at 95% power, The ADHD assessment questionnaire, based on that developed by DuPaul and colleagues29, consists of 18 items based on the DSM–IV ADHD diagnosis symptoms, with nine items assessing hyperactivity and impulsivity, and nine items assessing attentiveness. In the version used in the current study, participants were asked to choose whether each described situation was correct or incorrect with respect to themselves. Scores ranged from 0 to 9 on each of the two scales, with one point for each ADHD symptom. This questionnaire has been used to screen for ADHD in many studies (e.g.33). The internal consistency (Cronbach’s α) of the attentiveness section and of the hyperactivity-impulsivity section of the scale in the current study were 0.92 and 0.83, respectively. The DSM–V suggests that in individuals aged 17 and over the appearance of at least five symptoms (i.e. scoring 5 on this questionnaire) is sufficient for an ADHD diagnosis. However, in order to guarantee that the ADHD group in this study included only participants with this condition, we limited participation to individuals with six or more symptoms.The Symptom Checklist-90 (SCL-9034) was used to assess distress symptom occurrence rate with the purpose of excluding participants with psychiatric disturbances other than ADHD from the study. The SCL-90, completed during the screening phase of the experiment, is a 90-item, 5-point Likert scale questionnaire that measures the nine primary symptom dimensions of somatization, obsessive–compulsive, interpersonal sensitivity, depression, anxiety, hostility, phobic anxiety, paranoid ideation, and psychoticism. Patients are asked to rate the degree to which they have experienced symptoms within the last seven days. The retest reliability (correlation coefficients) of the symptom dimensions scales is r = 0.7–0.9. The SCL-90 has been translated into many languages and serves as an international standard.The structured clinical interview, using a modified version of the DISC-IV30 ADHD module, yields clinician-assessed symptom counts for hyperactive-impulsive and inattentive ADHD symptoms. Interviews were conducted by educational psychology graduate students extensively trained on DISC-IV administration and scoring, with scoring supervised by a senior clinical psychologist. The DISC-IV scoring algorithm determines the presence or absence of ADHD based on DSM-IV symptom count, age of onset, impairment, and other parameters .Actigraph sleep recordings were performed over five days using an actigraph , a wrist-worn ambulatory device that uses a piezoelectric element to measure wrist movements. The actigraph samples wrist activity levels at 10-s intervals, sums those across 1-min intervals, and translates the result into 1-min long epochs of sleep and wake. Additionally, participants were instructed to press a button on the actigraph when they began trying to fall asleep (determining bedtime), and when they woke in the morning (determining wake time), and to also keep a sleep diary documenting their bedtimes and morning wake-up times. Raw data was processed using the Actigraphic Scoring Analysis program  provided by the manufacturer to yield four sleep measures: total sleep time, sleep onset latency, wake time after sleep onset, and sleep efficiency . Daily actigraphy data were averaged to yield aggregated measures for each participant.The Pittsburgh Sleep Quality Index (PSQI) is an established tool for assessing subjective sleep quality36. The global PSQI score is determined by summing 18 items evaluating different aspects of sleep quality. A global PSQI score > 5 has been demonstrated to yield 89.6% diagnostic sensitivity and 86.5% specificity in distinguishing good and poor sleepers36, and thus can be considered a cut-off for clinically relevant sleep difficulties. The internal consistency (Cronbach’s α) of the PSQI was 0.66 in the current study.The Visual Oddball Task The stimuli were three geometric shapes  and photographs of three different male individuals’ faces. The set of photographs, taken from the standard NimStim face stimulus set37 of pictures of facial affect, showed each individual with an angry (target) and neutral (non-target) expression. Geometric shapes either had a black cross in the middle of the shape (target), or were “empty” (non-target). We used a four-stimulus visual oddball paradigm in which participants were shown regularly repeated standard stimuli  with 0.75 probability, and two “target” deviant stimuli (angry faces and shapes with a cross) with 0.25 probability. Each target stimulus was shown 10 times, and each non-target stimulus 30 times, resulting in a total of 240 stimuli . Stimulus presentation order was randomized between trials. In each trial, stimuli were displayed for 500 ms, followed by a 1000 ms inter-trial interval in which a blank screen was shown. The experiment, began with a short 32-trial practice block which contained stimuli corresponding to those presented in the experimental block. Similar oddball tasks have demonstrated high test–retest reliability38, and performing an oddball task several times in the same night was not shown to yield practice effects21.39, for the five days prior to the experimental trial, participants were instructed to go to bed every night between 23:00 and 24:00, wake up between 7:00 and 9:00, sleep at least seven hours per night, refrain from napping, and avoid drinking more than three caffeinated beverages per day. In order to monitor their sleep during this period and ensure that they went to bed as instructed, the participants wore an actigraph on each night. The experimental session began at 8 am of Day 6 and lasted until ~ 10:30 am on Day 7, during which time the participants (four to eight participants in each session) were kept continuously awake (> 25 h).As we have previously described41, during every visual oddball task session, each participant sat 80 cm from a 19-inch computer screen. The participant was instructed to focus his gaze on the stimuli to be presented at the center of the screen and, as quickly as possible without compromising accuracy, to indicate the occurrence of a “target” (deviant) stimulus by pressing the computer keyboard’s spacebar with his right index finger, while withholding response to the “non-target” (standard) stimuli. Reaction time and error rate were recorded. There were two categories of error: omission  and commission .At the beginning of the session the participants completed the PSQI, performed the visual oddball task (9:00–10:30 AM), and were then kept awake in the laboratory until they performed the visual oddball task again at 9:00 AM the next day. As previously describedResponses could be made during stimulus presentation as well as during inter-trial intervals.29, participants wore actigraphs on their wrist throughout the entire experimental session to verify that they remained awake and that they stayed under the laboratory’s controlled conditions . Participants did not smoke or consume food or beverages containing caffeine or cocoa, and were served organized meals at scheduled times under supervision. The participants were not permitted to perform any strenuous activity throughout the session, so when not being tested, they engaged in activities such as socializing and board games; participants of both study groups were involved equally in each of these activities. Experimental personnel present throughout the entire session ensured that no participant fell asleep. As this experiment was part of a larger study, participants’ emotional state and sleepiness were also tested throughout the experimental session.As we have previously describedp < 0.05) was determined following Bonferroni correction. These analyses were conducted using SPSS 25 software (SPSS Inc.).Before conducting any parametric tests, the normality assumption was examined (skewness and kurtosis between − 2 and + 2). Differences between the groups in the demographic variables and the pre-experimental sleep measures were examined using two-tailed independent samples t-tests or chi-squared tests. As multiple t-tests comparisons were performed, significance , we sought to perform a 2 × 2 × 2 mixed analyses of variance (ANOVA) on each of the four outcome variables . As these outcome variables of the oddball tests did not meet the normality assumptions, the aligned rank transform (ART) for nonparametric factorial ANOVAsIn each analysis the between-subject variables were time  target faces/shapes  or non-target faces/shapes  and group (ADHD/control), and the participant added as within-subject variable. These analyses were conducted using version 2.1.0 of ARTool in R environment (R version 4.0.5). No three-way interaction was detected (see below). Significant time × group interactions were further analyzed by conducting Wilcoxon signed-rank test in each of the study groups (ADHD and control).p < 0.05.In order to examine the interaction between target type (faces/shapes) and group (ADHD/control) at baseline (Hypothesis 2), mixed-model ANOVAs were conducted using the ART for nonparametric factorial ANOVAs. The between-subject variables were target faces/shapes  or non-target faces/shapes  and group (ADHD/control), and the participant added as within-subject variable. The significance threshold for all tests was set at Demographic comparisons between young adults with and without ADHD are presented in Table Descriptive statistics of the omission errors, commission errors, RTs, and RTSDs in response to face and shape targets among the ADHD and control groups before and after sleep deprivation are presented in Table  = 1.33, p = 0.251). However, there was a main effect for time  = 38. 63, p < 0.001), indicating that there were more errors following sleep deprivation than at baseline. There was, in addition, a significant time × group interaction  = 19.03, p < 0.001). To analyze this interaction, a Wilcoxon signed-rank test was conducted on each of the study groups, revealing that the increase in omission errors following sleep deprivation was significant in the ADHD group  but not in the control group .A 2 × 2 × 2 mixed nonparametric ANOVA was conducted, with the between-subject variables being time (baseline/time 0 + 25), target type (face/shape) and group (ADHD/control), and the participants being the within-subject variable. The analysis revealed no significant three-way interaction  = 3.92, p = 0.012), indicating that there were more omission errors in the ADHD group. Finally, there was no main effect for target type  = 0.29, p = 0.589), no time × target type interaction  = 2.46, p = 0.12), and no group × target type interaction  = 1.05, p = 0.307).There was also a main effect for group  = 0.38, p = 0.563). There was a main effect for target type  = 82.26, p < 0.001), indicating that reaction time was longer in response to non-target faces than in response to non-target shapes. However, there was no significant main effect for time  = 3.59, p = 0.061) or for group  = 0.35, p = 0.560). Similarly, there was no significant time × group interaction  = 1.33, p = 0.252), group × target type interaction  = 0.13, p = 0.721), or time × target type interaction  = 1.50, p = 0.224).Analysis of the reaction time in response to target faces and target shapes via a 2 × 2 × 2 mixed nonparametric ANOVA revealed no significant three-way interaction  = 0.87, p = 0.354). However, there was a main effect for time  = 43.06, p < 0.001), indicating that RTSD increased following sleep deprivation. In addition, there was a significant time × group interaction  = 25.11, p < 0.001). To analyze this interaction, a Wilcoxon signed-rank test was conducted on each of the study groups, revealing that the increase in RTSD following sleep deprivation was significant in the ADHD group  but not in the control group .There was also a main effect for group  = 9.84, p = 0.004), indicating that RTSD in response to targets was higher in the ADHD group. There was also a main effect for target type  = 29.60, p > 0.001), indicating that RTSD was higher in response to target faces rather than to target shapes. Finally, there was no group × target type interaction  = 1.12, p = 0.293).Analysis of the reaction time variability in response to target faces and target shapes via a 2 × 2 × 2 mixed nonparametric ANOVA revealed no significant three-way interaction  = 0.04, p = 0.841). However, there was a main effect for time  = 21.17, p < 0.001 = 12.76, p < 0.001). To analyze this interaction, a Wilcoxon signed-rank test was conducted on each of the study groups, revealing that the increase in commission errors following sleep deprivation was significant in the ADHD group  but not in the control group .Analysis of the commission errors in response to non-target faces via a 2 × 2 × 2 mixed nonparametric ANOVA revealed no significant three-way interaction  = 13.98, p < 0.001), indicating that there were more commission errors in response to non-target faces rather than non-target shapes. There was also a main effect for group  = 6.31, p = 0.017). Finally, there was no group × target type interaction  = 0.01, p = 0.918), or time × target type interaction  = 0.36, p = 0.552).There was also a main effect for target type  = 6.54, p = 0.015; commission: F = 28.34, p < 0.001). The rates of omission errors in response to target faces was higher than in response to target shapes, and the rates of commission errors in response to the non-target faces higher than in response to the non-target shapes. There was no main effect for group  = 0.99, p = 0.330; commission: F = 0.42, p = 0.522) or target type × group interaction  = 0.94, p = 0.340; commission: F = 0.09, p = 0.767).Mixed nonparametric ANOVAs on omission and commission errors at baseline revealed a main effect for target type (faces/shapes)  = 100.68, p < 0.001) and higher mean RTSD  = 14.11, p < 0.001) in response to target faces than in response to target shapes. There was no main effect for group  = 0.01, p = 0.920; RTSD: F = 0.23, p = 0.633) or target type × group interaction  = 2.39, p = 0.132; RTSD: F = 0.038, p = 0.848).Similarly, mixed nonparametric ANOVAs on the RT and RTSD at baseline revealed a main effect for target type (faces/shapes), with longer mean RT  on the processing of emotional facial expressions (angry faces) and non-facial stimuli (geometric shapes) as reflected in the visual oddball paradigm. Specifically, the visual oddball paradigm examines the process that allows for the maintenance of response persistence over time  to visual stimuli, with decreased sustained attention reflected by lower reaction time to the stimuli (RT), instability in the reaction time to the stimuli (RTSD), and difficulties in detecting the target stimuli and in response inhibition to the non-target stimuli.43.Our first hypothesis was that following sleep deprivation, performance on the oddball task would deteriorate, as reflected by lower sustained attention  and decreased response inhibition (higher rates of commission errors). We expected the level of deterioration to be higher in the ADHD group than the control group and in response to facial rather than non-facial stimuli. This hypothesis was partly confirmed. As hypothesized, sleep deprivation had a greater effect on the performance of the ADHD group than on the control group. Specifically, as reflected by significant time × group interactions, sleep deprivation significantly increased the rates of omission errors and commission errors, and the levels of RTSD, in the ADHD group but not in the control group. Sleep deprivation, however, did not significantly affect RT to the target stimuli, which may imply that sleep deprivation increases instability in the reaction time to visual stimuli without causing an overall increase in the reaction times. In this regard, it is noteworthy that the lack of difference between the RTs of the ADHD group and the RTs of the control group is in line with several meta-analyses reporting that the RTs of individuals with ADHD are not necessarily slower than those of individuals without ADHD but tend to be far less stable22 and children20 and with reports stating that sleep difficulties aggravate impulsivity and inattentiveness in children and adults with ADHD27. However, the finding that ADHD is associated with greater sensitivity to the negative effects of sleep deprivation on sustained attention and response inhibition is novel. In previous studies, which used continuous performance tests (CPT), sleep deprivation was found to increase omission errors, commission errors, and RTSD among participants with and without ADHD, with no significant differences between the groups in terms of the magnitude of this increase22. The reason for the disparity between the results of these studies and the current study is likely due to the differences between the CPT used in the former and the oddball task used here. Most significantly, the CPT task comprised of one circle and one triangle, whereas the oddball task included a more complex set of stimuli: two facial expressions and different geometric shapes. It is possible that following sleep deprivation, individuals without ADHD fail to sustain attention when engaged in a simple and monotonous task but a more challenging and demanding task prompts them to employ their attentional resources. Individuals with ADHD, on the other hand, fail to sustain attention following sleep deprivation regardless of such characteristics of the task.The finding that sleep deprivation has deleterious effects on sustained attention and response inhibition is consistent with previous controlled studies conducted among young adults45, which plays a central role in sustained attention. Notably, ADHD is associated with lower activation in the prefrontal cortex during tasks that involve attention46 and inhibitory control tasks47. Thus, sleep deprivation may aggravate the deficits in the functioning of the prefrontal cortex and related regions, leading to a more severe disruption in the performance of tasks that require sustained attention.The reasons for the heightened vulnerability of individuals with ADHD to the effects of sleep deprivation on sustained attention are unclear but possibly involve deficits in brain systems that are involved in attention and response inhibition and are sensitive to the effects of sleep deprivation. Specifically, sleep deprivation attenuates activation of various parietal and frontal cortical regions, including the prefrontal cortex17 and may be attributed to the greater complexity and/or added emotional content of facial stimuli.As expected, participants with and without ADHD demonstrated slower RTs, and greater RTSD (but not a significantly higher rate of omission errors) in response to facial targets than in response to non-facial targets and more commission errors in response to facial non-targets than in response to non-facial targets on baseline as well as following sleep deprivation. The findings regarding RTs, RTSD, and commission errors are consistent with previous studiesHowever, in contrast to our hypothesis, the lack of time × group × target type interactions and time × target type interactions indicates that sleep deprivation had a similar effect on participants’ sustained attention capabilities and response inhibition regardless of whether facial or non-facial stimuli served as targets and non-targets. It can thus be concluded that for individuals with ADHD sleep deprivation affects the sustained attention to visual stimuli in general and not to processes that are specific to facial features or the emotional content of facial expressions.38. In particular, Raz and Dan17 used the same protocol as the current study (but without sleep deprivation) and showed that participants with ADHD had higher rates of omissions, slower RTs, and higher RTSDs in response to facial and non-facial targets than participants without ADHD. The main difference between the current study and similar previous studies was that the current study attempted to control for the participants’ sleep quality and quantity at baseline. This was done because individuals with ADHD tend to suffer more than individuals without ADHD from poor sleep and excessive daytime sleepiness49, with the most common sleep difficulty associated with ADHD being a delayed sleep/wake cycle52, resulting in shorter sleep duration and accumulated sleep propensity48. We therefore limited participation in the current study to people without known sleep disorders, and the participants were instructed to go to bed every night between 23:00 and 24:00, wake up between 7:00 and 9:00, and sleep at least seven hours per night for the five days prior to the experimental trial. Adherence to these instructions were verified using actigraphy. It is therefore possible that deficits in sustained attention and response inhibition among individuals with ADHD are due, at least partially, to sleep difficulties and conditions of insufficient sleep. This possibility is supported by studies demonstrating that individuals with ADHD not only tend to suffer more than individuals without ADHD from poor sleep and excessive daytime sleepiness49 but are also more sensitive to the effects of sleep deprivation on sleepiness39. Sleep deprivation and/or increased sleepiness have been shown to be associated with impaired cognitive functioning53, reduced ability to accurately identify emotional expressions54, and functional decline in brain areas involved in conscious visual cognition of facial expressions55.Taken together, the findings of the current study suggest that people with ADHD are more sensitive to the effects of sleep deprivation on sustained attention and cognitive functions that rely on attention, including the accurate identification of emotional facial expressions. Given that ADHD is associated with poor sleep and excessive daytime sleepiness48, it is feasible that poor sleep quality and quantity play an important role in the difficulties in sustained attention and, consequently, in the ability to accurately attend to emotional facial expressions that characterize many individuals with ADHD.Our second hypothesis was that prior to sleep deprivation  participants with ADHD would perform worse than controls in the measures of the oddball task. There were, however, no differences between the groups in any of these measures. This result contrasts with previous studies which demonstrated that adults with ADHD perform more poorly than adults without ADHD in similar tasks that require sustained attention and response inhibition53. Increased difficulties in the interpretation of emotional facial expression due to deficits in sustained attention resulting from insufficient sleep may contribute to the social, interpersonal, and emotional difficulties that are associated with ADHD in adulthood55. Hence, ensuring sufficient sleep and avoiding conditions of sleep deprivation may be critical elements in ADHD treatment. Supporting this assertion, Lopez et al.56 reviewed 14 randomized controlled trials evaluating the effects of cognitive-behavioral therapies for insomnia (CBT-I) on adults with ADHD, demonstrating that these interventions consistently reduced the severity of core ADHD symptoms.The finding that sleep deprivation hinders the ability of individuals with ADHD to sustain attention to visual stimuli, including emotional facial expressions, has important clinical implications. First, it implies that insufficient sleep, whether due to sleep difficulties or an irregular sleep schedule, may impair the cognitive functioning of individuals with ADHD to a greater degree than individuals without ADHD. This has obvious negative consequences on academic and professional performance and an increased risk of accidents. Second, emotional facial expressions are a critical cue for accurately perceiving others’ emotions, which is essential for adequate social interactions58. Thus, more research is needed to determine the effects of sleep deprivation on the processing of facial expressions other than anger in individuals with ADHD. Second, only young men were included in the study in order to lower variability and assure adequate statistical power for examining the study’s main hypotheses. Thus, generalization of the findings to women and other age groups should be made with caution. Third, 25 h of sustained wakefulness is an extreme condition of sleep deprivation which is not commonly experienced by young adults. A much more common condition among this population is chronic insufficient sleep59. Thus, additional examination is required to elucidate whether such limited sleep deprivation produces the effects observed in the current study. Fourth, our exclusion of participants with periodic limb movements in sleep, obstructive sleep apnea, or restless legs syndrome was based on subjective self-reports. A more definite elimination of such disorders requires objective tests, such as polysomnography, which were not conducted in the current study. Fifth, it could be argued that it was the repetition of the oddball task rather than the lack of sleep that affected the performance of the participants. However, this is unlikely as similar oddball tasks have demonstrated high test–retest reliability with no indication of a practice effect among participants with and without ADHD38. In particular, in Sedah et al.’s study21, participants performed a similar oddball task once in the morning and once in the evening with the order being counter balanced. The results indicated a good test–retest reliability and no notable differences between the two trials. Finally, during the 24 h preceding the experimental session, the participants of the ADHD group did not take ADHD stimulant medications (a washout period was used for such medications in previous studies60). Thus, rebound effects or withdrawal symptoms might have affected the performance of some participants. Nevertheless, only limited, if any, rebound or withdrawal effects among adult ADHD patients were reported in studies examining the effects of discontinuation of treatment with such medications62.The current study has several limitations. First, only one emotional facial expression (anger) was used. Previous studies have shown that the existence or the gravity of deficits in emotional facial expression processing (associated with ADHD or sleep deprivation) may depend on the type of emotion expressedIn conclusion, the current study suggests that sleep deprivation has a detrimental effect on sustained attention to visual stimuli, including emotional facial expressions, of young male adults with ADHD. These results further support the proposition that sleep quantity and quality have a substantial effect on the severity of ADHD symptoms.


Yoga has been shown to play a role in reducing the symptoms associated with the inattentive and hyperactive-impulsive forms of attention-deficit/hyperactivity disorder (ADHD). The medical history and clinical findings for a nine-year-old patient presenting with difficulty paying attention and impulsive speech and actions at home and school are presented. After the diagnosis of combination type ADHD by assessment of DSM-5 criteria, both at home and school and through parent and teacher evaluations using National Institute for Children’s Health Quality (NICHQ) Vanderbilt Assessment Scales, the patient initiated a yoga training regimen. Six months after initiating the yoga training regimen, follow-up parent and teacher questionnaires revealed improvement in both the inattentive and hyperactive-impulsive symptoms. Literature sourced from the PubMed database to explore the efficacy of yoga for ADHD was used to support the research hypothesis that a structured yoga training regimen improves the symptoms associated with the inattentive and hyperactive-impulsive forms of ADHD, and thus, yoga is recommended as a management technique for individuals with ADHD. Attention-deficit/hyperactivity disorder (ADHD) is a neurological disorder characterized by difficulties in paying attention, excessive activity, or controlling behaviour, that is not appropriate for a person's age . ADHD isADHD is usually diagnosed in about 3% to 7% of school-age children . It is iYoga therapyYoga is a mind-body therapy that can benefit health by regulating attention, decreasing psychological stress, and self-regulation . ThroughWe present the case of a nine-year-old South Asian male who was seen with his parents for the evaluation of a two-year history of experiencing symptoms associated with ADHD. This individual was recruited from a yoga centre in the Greater Toronto Area and was not on any other interventions to manage his ADHD symptoms, at the time of the yoga intervention. His parents and school teacher observed frequent instances of fidgeting, difficulty remaining seated during mealtime and class, frequent talking and interruptions, and difficulty waiting turns. They also observed declining school performance over two years, frequent careless mistakes in schoolwork, difficulty completing homework and chores, and frequently misplacing toys and schoolbooks. He had no past medical or psychiatric history such as central nervous system infections, seizures, recurrent otitis media, mood disorders, anxiety, or conduct disorder. Birth history revealed no perinatal infections or complications, or perinatal exposure to tobacco, drugs or alcohol. Medication history for both prescribed or over-the-counter drugs was negative. In terms of family history, his father also struggled with ADHD as well as major depressive disorder. A physical examination revealed a healing superficial abrasion of the left knee from a recent fall. Further cardiac examination revealed a regular rate and rhythm, no murmurs, rubs, gallops or other cardiac abnormalities. A neuropsychiatric exam revealed a person who was oriented to person, place and time, with an agitated demeanour and poor eye contact. He spoke at a fast rate, and his mood was nervous, while his speech and thought process were coherent, and no auditory or visual hallucinations were noted. NICHQ Vanderbilt Assessment Scale assessments were collected from both the patient’s parents and teacher. The initial parent questionnaire revealed that the child’s total symptom score was 45 and the average performance score was 4.5. In the teacher’s assessment of the child, the child scored 44 on the total symptom score and 4.25 on the average performance score. The results of these questionnaires were indicative of the diagnosis of ADHD. The parents refused any pharmacologic therapy for their child’s ADHD, instead opting to enrol their child in a daily, online evening yoga program conducted through Skype, where the child performed a set of asanas that are outlined in Table Each asana can help with either concentration, aggression, anxiety or self-esteem . FurtherAt the six-month follow-up after initiating the yoga training regimen, the parents noted subjective improvement in their child’s ADHD symptoms. His parents and school teachers observed decreased instances of fidgeting, improved ability to remain seated during mealtime and during class, improved ability to complete homework and chores and improved school performance. The follow-up teacher questionnaire which was obtained after six months revealed a total symptom score of 27/54 and the average performance score for questions was 3.25 Tables .To put our case in context, a literature search on PubMed was used to identify five studies that investigated yoga as an alternative or complementary therapy for the treatment of ADHD. A total of 145 study participants, across five studies, were considered. All studies were performed in the paediatric population, ranging from ages three to 16.A review paper by Mehta et al. investigated the efficacy of yoga on improving ADHD symptoms as a low-cost approach to ADHD that is useful to treat children in developing countries . ResearcAnother study, conducted by Beart and Lessing explored the impact of yoga on the concentration and behaviour of 10 attention deficit hyperactivity disorder (ADHD) patients, using parent and teacher assessments [The next study, conducted by Harrison et al, investigated the efficacy of Sahaja yoga meditation on the management of ADHD in children . Forty-eVarambally et al. examined yoga as a complementary therapy in children with moderate to severe ADHD . The stuIn a more recent study, yoga was evaluated as front-line behavioural therapy for the management of ADHD symptoms in preschoolers aged three to five years old . This miIn conclusion, it is recommended that yoga be used as a complementary therapy to medication so that doses can be lowered or eliminated. Our case study exemplified the effectiveness of using yoga as a standalone treatment for ADHD, as improved ADHD and performance scores were observed in the individual. Further research should be conducted on the effectiveness of each asana on ADHD to create an ideal yoga routine for individuals to use to manage their symptoms. Studies with a larger number of participants should also be conducted to compare the effectiveness of yoga in medicated and unmedicated ADHD patients. More importantly, research on ADHD should continue to be done as we still do not have a clear understanding of the nature of the disease. Furthermore, with mental health on the rise as a result of the pandemic, yoga can be further explored to analyse the benefits it has in reducing stress and improving focus and concentration in a remote learning and working environment.


Surfactants are crystallizing a certain focus for consumer interest, and their market is still expected to grow by 4 to 5% each year. Most of the time these surfactants are of petroleum origin and are not often biodegradable. Cashew Nut Shell Liquid (CNSL) is a promising non-edible renewable resource, directly extracted from the shell of the cashew nut. The interesting structure of CNSL and its components  lead to the synthesis of biobased surfactants. Indeed, non-ionic, anionic, cationic and zwitterionic surfactants based on CNSL have been reported in the literature. Even now, CNSL is absent or barely mentioned in specialized review or chapters talking about synthetic biobased surfactants. Thus, this review focuses on CNSL as a building block for the synthesis of surfactants. In the first part, it describes and criticizes the synthesis of molecules and in the second part, it compares the efficiency and the properties  of the obtained products with each other and with commercial ones. Our world and the societies that we have built are going through a major phase of great change punctuated by increasingly frequent and violent crises. The threat of climate change and all the economic, political, and ecological upheavals it brings, impact collective consciousness, and influence future development strategies. Not only consumers, but also countries and industries, are increasingly sensitive to the origin of the products they buy, the impact of their production processes, their effects on human health and on the environment. They are also concerned about the end of life of these products, their possible recycling, or the pollution they can cause. The world of chemistry, the nerve center of the creation of our daily products, is naturally alert to these questions. The use of and access to fossil resources, increasingly complex or even controversial, are gradually giving way to the biobased building blocks ,2.Numerous studies are bringing to light the possible toxicity of currently widely used products such as pesticide , and addIn these times, when components and additives are deeply studied, scrutinized, and criticized, surfactants are crystallizing a certain focus for consumer interest. Present in our shampoos, our detergents, our household products, our cosmetics, and also in the world of construction and materials, their omnipresence and their possible impact are worrying. Their proximity to our body, our food, and the water we consume make surfactants a potential source of pollution and danger for humans, but also for rivers, oceans, sealife, wildlife, and flora on which we depend, and for which we are responsible ,12,13. For the past ten years, we have seen the blooming of possible alternatives to current industrial surfactant products. There is also an upsurge in homemade soap, laundry, cosmetics, and detergents. The compositions of which are made up of easily accessible and natural ingredients. In contrast, within academic research , there iMany bioresources such as sugar ,15, vegeThis topic is complex. Moreover, some so-called “biobased” products are often only partially biobased. Finally, the “green” solutions proposed must be able to be industrialized in the long term without endangering the wildlife and without competing with crops linked to human or animal food.CNSL (Cashew NutShell Liquid) is a versatile abundant bioresource already used to synthesize surfactants. Even now, CNSL is absent or barely mentioned in specialized review or chapters talking about synthetic biobased surfactant ,22,23. AAfter a general introduction about what, exactly, CNSL is, we will first describe and criticize the synthesis of surfactants currently made using this feedstock. Next, we will discuss the properties of these surfactants and then, finally, we will give our conclusions and our perspectives on the future advances of these green CSNL-based surfactants.2 extraction . Ot. Ot83]. In contrast to the above-mentioned surfactants, the present anionic molecules contain sulfonate group in alkyl chain of the spacer instead of aromatic position . CardanoThe strategy of sultone was employed to modify cardanol poly(oxyethylene) ethers (CPE) , where aTo conclude, for cardanol sulfonated surfactants, sulfonate group is either directly on the aromatic ring or at the end of an alkyl or polymer chain. Gemini sulfonate surfactants were also reported. However, some of the reactants used , sodium chloroacetate, sultones,) used are toxic or CMR, hence some of the synthesis routes should be improved. In addition, what is often called bio-based surfactant is in fact, very often only partially  bio-based.This section summarizes the different pathways to functionalize cardanol by a cationic group to obtain amphiphilic molecules. The first data on cationic derivatives appeared in 1964; this preliminary research was followed by several publications and patents. The cationic part of these molecules was exclusively represented by ammonium, pyridinium and imidazolium groups, which we will describe in this section.Cashew nutshell liquid (CNSL) has been used for the first time to prepare quaternary ammonium salts with the aim of obtaining water soluble compounds with germicidal properties . Several decades later, quaternary ammonium salts used as a phase transfer agent were prepared in five steps starting from cardanol .3). The primary amine hydrochloride was treated with different iodide compounds  to give the quaternary ammonium salts  octane . The reaFinally, using a different method, the same authors reported the preparation of half biobased cationic surfactants with hydroxyl functions and heterocycles. The alkylation of hydrogenated cardanol was performed with epichlorhydrin, a CMR reactant, followed by epoxy ring opening with protonated N-methylmorpholine .In 2020, using hydrogenated cardanol (3-pentadecyl phenol), similar structures  were obtTheses 60–65% biobased cationic surfactants were assessed for their biocompatibility and their potential to solubilize curcumin as a model drug, which has poorly water solubility.A polyfunctional half biobased cationic surfactant was synthesized from cardanol in very good yield after 2 steps. This sequence began by simple alkylation of the phenol by a halogenated aliphatic amine under basic conditions. The primary amine of the cardanol derivative was used for an opening reaction of N-trimethylammoniumglycidyl chloride, a CMR molecule, in 96% yield. Thus, an ammonium was introduced in this step to generate a new surfactant bearing two other polar functions with a secondary amine and an alcohol  48]..48].The polyfunctionality of this cationic surfactant is a real advantage with a very interesting solubility in pure water.Very recently, a patent followed by a publication provided a series of 45–65% biobased hydroxylated cardanol ammonium salts with one or two hydroxyl groups . These sCardanol was modified to N-benzyl-N,N-dimethyl-3-pentadecylclohexan-1-ammonium, in 2 steps with an overall yield of 51% . The useAnother patent reported the preparation of 60% biobased cardanol-derived ammonium surfactants by epoxy ring opening reaction with different (sometimes toxic) allylamine as diallylmethylamine, triallylamine or diallylamine, the chemical structures are represented below  108]. T. T108]. Amphiphilic poly(ionic liquid)s C-29a and C-29-b  were obtIn a recent research work, an antimicrobial cationic agent obtained in three steps from cardanol was embedded in UV curable epoxy acrylate system to develop antibacterial coatings . The bro2CO3 or KOH). Further, the pyridinium salts were obtained after reaction with pyridine, not the friendliest solvents -3-pentadecylbenzene  111]. I. I111]. Recently, a patent described the preparation of different surfactants with bipyridinium polar groups. After alkylation of hydrogenated phenol with 1,4-dibromobut-2-ene, the surfactants were obtained by a second alkylation reaction with different salts obtained from 4-4′-bipyridine  109]. I. I109]. N-methylimidazole.Using the same procedure as previously described , a serieA second study reported the preparation of imidazolium-based ionic liquid from cardanol . After dThe amphiphilic character of this product was not directly mentioned by the authors, but they used its self-assembly properties to design thermotropic and lyotropic phases. This 50% biobased ionic liquid crystal is an efficient electrolyte for energy storage devices.Several cationic surfactants were, essentially, synthesized from cardanol, which was almost the only molecule bio-based in these reactions. In addition to the use of CMR or toxic reagents, the structure of these molecules such as quaternary ammonium leads us to reflect on the possible toxicity of these new surfactants. Unfortunately, little information on this subject, to our knowledge, has yet been disclosed.Pyrazolium and thiazolium surfactants were prepared in two steps from hydrogenated cardanol. As previously described, alkylation of phenol by 1,4-dibromobut-2-ene in basic conditions gave halogenated cardanol derivative . Then, rA second example of thiazolium surfactant was obtained in two steps by reaction of cardanol with epichlorohydrin followed by epoxy ring opening with protonated thiazole .Zwitterionic surfactants are organic compounds exhibiting an apolar aliphatic chain and a polar head group with a positive and negative charge. This particularity provides them very advantageous properties compared to conventional cationic or anionic surfactants. Usually, zwitterionic surfactants possess valuable antibacterial and fungicidal activity combined to good compatibility with a large range of surfactants. These salts are known for their robust structure, high tolerance to salinity and temperature. Moreover, zwitterionic surfactants have low toxicity which makes them almost non-irritating to the skin and eyes. Thus, these foaming agents can be used in mild shampoos and skin cleansers. Several other interesting and complementary properties should also be noted: these zwitterions are classified as antistatic and emulsifying agents with a good dispersibility, wettability and biocompatibility.To date, very few examples have described zwitterionic surfactants derived from CNSL oil. All studies used cardanol as a raw material with a cationic part resulting from a quaternized amine or introduced by a ring opening. Concerning the anionic part, a carboxylic or sulfonate anion was mainly used. To this end, phenol represents a very promising reactive function for developing zwitterionic surfactants by simple etherification. From this postulate, some pathways were developed in recent years, which we will summarize in this section.2O. In presence of NaHCO3, betaine 2-(dimethyl(3-pentadecyl-cyclohexyl)ammonium)acetate Z-2 was prepared in moderate yield (light brown solid). This synthesis led to a 74% biobased aliphatic betaine in only two steps.Several 3-Pentadecylcyclohexylamines were synthesized from CNSL by reductive amination in water . In thisN-trimethylammoniumglycidyl chloride (1 equiv). This sequence afforded a poorly (46%) biobased surfactant as a mixture with predominantly an unsaturated aliphatic chain of one to three alkenes.Recently, zwitterionic surfactant based on cardanol was synthesized in three steps with an overall yield of 65%  48]. Fi. Fi48]. In 2019, a series of copolymers containing sulfobetaine and cardanol was synthesized via free radical polymerization of methacrylate derivatives  113]. A. A113]. 2N  was achieved giving cardanol dialkylamine in very good yield. In 2015 , zwitter4N+Br−, Bu4N+Cl−, BnEt3N+Cl−, C12H25Me3N+Cl− or C14H29Me3N+Cl. Depending on the catalyst, cardanol was heated in alcoholic solvent  to give cardanol chlorohydrin ether in very good yield. To the previous compound were added diphenylamine (excess) and organic base (Et3N or pyridine) in similar protic solvent to afford tertiary amine after heating for a few hours. The last step used sodium 3-chloro-2-hydroxypropane sulfonate (excess) as alkylating reagent to yield a 66% biobased zwitterionic surfactant. The Very recently, two patents provided a temperature-resistant salt-resistant cardanol zwitterionic surfactants ,116. In 3- to C5H11-) and cardanol. As an example, tertiary amine (1 equiv) and 4-chloro-3-hydroxy-butyric acid (2 equiv) were heated in ethanol several hours to give zwitterionic cardanol Z-8 in good yield.Based on a very similar strategy, another sequence was described to provide a 74% biobased cardanol surfactants in three steps . To thisTo date, our knowledge about the zwitterionic surfactant is limited to these examples with few information on their properties and applications. All the syntheses require two or three steps to generate the polar head. We can note that all these salts have an alcohol and/or phenol function, in addition to the positive and negative charges. To facilitate the synthesis and purification of the products, these different studies employ the same strategy by using the final step to simultaneously generate the two charges on the cardanol derivative. All these syntheses involve the use of common, but toxic, and/or CMR, reagents such as epichlorohydrin, 1,3-propanesultone, glycidyl methacrylate and so on. These sequences should be revisited to be more ecologically friendly. In addition, the cardanol block-building is almost the only biobased part of the surfactant that sometimes halves the biobased contribution in the synthesis of the surfactant.Nonionic surfactants are molecules that do not undergo ionization when being dissolved in water. They exhibit high stability in solution, good solubility in both water and organic solvents, and excellent compatibility with other surfactants. This section describes the different synthesis of nonionic surfactants based on CNSL. All these surfactants have a hydrophilic part such as poly(ethylene oxide) or PEO, polyoxazoline and/or sugar groups. According to the nature of the polar head, nonionic surfactants can be partially or totally biobased.These molecules are made of cardanol or cardol as the biobased hydrophobic part and PEO or polyoxazoline as the non-biobased polar head.Ethoxylation of cardanol ,124,125 2CO3, Ca(OH)2 or NaHCO3. Ethoxylation was also carried out with acetic acid as a catalyst. The degree of ethoxylation (m), and thereby the length of the hydrophilic part, was controlled by the molar ratio between cardanol and ethylene oxide octane as part of the spacer (molecules C-11 and C-12): C20 of derivatives C-11 and C-12 were 5.40 × 10−6 mol/L and 4.00 × 10−6 mol/L, respectively. Commercial surfactants CTAB and cetylpyridinium chloride show C20 values of 4.07 × 10−4 mol/L and 3.55 × 10−4 mol/L, respectively [Notably, γfactants , whereasower see . Surfacei et al.  compared−3 mol/L  and 1.99−4 mol/L , respect−4 mol/L  reportedectively . Gemini It is well known that the type of spacer affects Gemini surface behavior. Wang et al.  synthesi4 or C6 chain as the second tail (molecules C-11 and C-12). Both derivatives possessed similar CMC values, which were in the same order of magnitude than other cationic Gemini surfactants. It was observed that Krafft temperature (TK) of molecule C-12 with C6 tail (TK > 90 °C) was much higher than those of molecule C-11 with C4 tail (TK = 3 °C). Increasing the length of one hydrophobic tail led to a decrease in the solubility of such compound in water, which explains the higher TK of derivative C-12.All CNSL-based Gemini surfactants described in the literature have been produced with cardanol as the hydrophobic tail. Therefore, it is not possible to study the influence of the phenolic compound  on the surface properties of such molecules. One study  describeSome applications of such Gemini surfactants are depicted here. First, three Chinese patents ,94,126 aSome Gemini CNSL derivatives exhibited interesting antimicrobial activities. For example, anionic molecules A-16 showed favorable antimicrobial properties against both Gram-positive and Gram-negative bacteria, such as S. aureus or E. coli. These surfactants were also efficient against fungi such as A. niger, C. albicans or A. flavus. The authors  concludeIts natural abundance and the biological activity of the molecules that compose it are undeniable strengths of CNSL. Anacardic acid is well known as an antibacterial and antifungal agent ,171,172.However, there is a trade-off between biological activity and cytotoxicity. Most surfactants will be used in contact with skin and hair, or end up in an aquatic environment. Despite the efforts of some authors to demonstrate the non-cytotoxicity of their molecules ,111,174 The synthesis of zwitterionic copolymers Z-4 with cardanol and a significant proportion of sulfobetaine core not only revealed excellent bactericidal properties, but also an interesting adhesion resistance to proteins, bacteria and cells, with sufficient biocompatibility . When thThe end of life of a product is also very important. CNSL and its compounds are biodegradable even if there are, to our knowledge, few articles on this subject. Unfortunately, little information or study about the biodegradability of surfactants derived from CNSL are available, even though these products are often relegated to our ecosystem after use. However, a particular interest in ethoxylated compounds can be noted. Indeed, several studies showed and confirmed the biodegradability of these derivatives. Tyman et al.  studied CMC and, when available, C20 and/or TK of ionic and nonionic single chain CNSL derivatives to commercial products.To better understand the potential of CNSL-based surfactants for industrial applications, we compared literature values of CMC, γ−4 and 8.10 × 10−3 mol/L. These values are close to CMC of commercial carboxylated products such as sodium stearate and SLSA. Surface tension values are ranging from 28.38 to 43.53 mN/m, which are of the same order of magnitude than commercial ones. Moreover, some carboxylated molecules (A-1 and A-2) are characterized by TK lower than 5 °C, which make them interesting for industrial processes requiring low temperature. As for sulfonated CNSL derivatives, their CMC are comprised respectively between 1.70 × 10−5 and 8.35 × 10−3 mol/L , which are lower than SDS and SDBS. We noted a surprising and unlikely CMC value for A-9 with 372 mmol/L [CMC values range from 31 to 42 mN/m, such as commercial anionic products. Super spreadability or super wettability aromatic siloxane sulfonated surfactants A-14 and A-15 were characterized with low γCMC values of 18–24 mN/m. Therefore, anionic CNSL-based surfactants can be as effective as commercial ones. To the best of our knowledge, many patents report the synthesis and/or applications of anionic CNSL-based surfactants, which show their industrial potential as biobased alternatives to petroleum products.Carboxylated CNSL-based surfactants are characterized by CMC between 8.30 × 102 mmol/L . As prev−7 and 8.00 × 10−4 mol/L and γCMC varying from 11.32 to 43.2 mN/m, whatever the nature of the polar head . Globally, their surface parameters are much lower than commercial cationic surfactants  and <0 °C, respectively. Therefore, this CNSL surfactant shows promising potential as an alternative to commercial zwitterionic products.Notably, γ−6 mol/L to 10−4 mol/L. These values are lower or close to the commercial ones (TergitolTM NP-9 and TritonTM X-100). Additionally, γ are generally comprised between 32  and 53 mN/m, with no clear trend between the surface tension and the surfactant structure. Some of these biobased molecules can replace petroleum-based commercial surfactants, such as TergitolTM NP-9. CNSL derivatives with saccharide head show higher CMC than their analogs with PEO or polyoxazoline hydrophilic groups, whereas γ values are of the same order of magnitude. Comparison between CNSL-based and commercial saccharide surfactants (such as TritonTM CG-600) is tricky, because of a lack of data regarding CMC values in the literature. It can be noticed that CNSL derivatives with glucose or glucosamine are characterized by much larger CMC (between 1100 and 4100 mg/L) than TritonTM CG-600 (CMC = 74 mg/L), which seems to point out that these molecules are less effective than the commercial one. Yet, CNSL derivatives with amylose as polar head exhibit CMC (in mol/L) and γ close to commercial TritonTM X-100. The latter was classed in the Authorization List (Annex XIV) of the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) because of one ecotoxic degradation product. CNSL-based molecules with amylose head can, therefore, be an interesting alternative to such surfactants. More than 20 patterns report the synthesis and/or application of nonionic CNSL-based surfactants, especially ethoxylated molecules. Moreover, some of them are sold by Cardolite or K2p Chemicals. This fact points out the interest of such compounds by the industrial actors as biobased, non-toxic, and biodegradable alternatives of petroleum-products such as nonylphenol ethoxylate surfactants.Ethoxylated and polyoxazoline CNSL surfactants exhibit CMC ranging from 10CNSL-bases surfactants have found various uses in many fields such as detergency, polymerization emulsion, enhanced oil recovery or antimicrobial products. Some applications of these compounds are described in this section.TM NP-10). A washing test on soiled cotton fabric proved that NI-4 has similar performances to petroleum-based TergitolTM NP-10. Similar results were described by Zhu [CNSL surfactants can be employed in formulation of detergency solutions ,178,179.d by Zhu  in compaNonionic ethoxylated CNSL surfactants were also used as surfactant in cement formulation  or in ha2 and bipyridine. To obtain a better emulsion stability, a mixture of these two surfactants was used and the polymerization afforded a stable latex. According to Caillol et al. [Another example of the application of CNSL derivatives is their use as stabilizer, especially for polymerization emulsion. The carboxylated surfactant A-5 based on benzoxazine ring was employed for the preparation of polystyrene latex. It offered high efficiency for the stabilization of emulsion. Anionic surfactant A-19a, with n = 1 and 2, were successfully utilized by Jayakannan et al.  as strucl et al. , zwitterl et al.  used a bSome CNSL surfactants were employed as demulsifier agents ,130,131 Notably, Z-7 and Z-8, polyaromatic cardanol zwitterionic surfactants have demonstrated good temperature resistance, salt resistance and interface activity. A water solution of these cardanol zwitterionic surfactants can have ultralow interfacial tension with crude oil, so that the cardanol zwitterionic surfactant has a good application prospect in several oil reservoirs with high temperatures and high mineralization degrees.S. aureus, B. subtilis and E. coli [Several studies reported the antibacterial properties of cationic surfactants obtained from cardanol. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of cardanol surfactants with ammonium and thiazolium groups  were determined against  E. coli . It was S. aureus), 77.12% for gram-negative bacteria (E. coli) and 77.82% for yeast . Cationic surfactants  can be used to disperse nanomaterials as single-walled carbon nanotubes in aqueous solution, because benzene rings and aliphatic chains enable strong π-stacking interaction on carbon nanotubes. Surfactants prepared from cardanol by introduction of ammonium or pyridinium groups are better for carbon nanotubes dispersion than the classical anionic surfactant, dodecylbenzene sulfonate sodium (SDBS). In addition, carbon nanotubes dispersed with cardanol-derived surfactants demonstrate significantly improved antibacterial properties against E. coli and S. aureus. The antibacterial activities are attributed to positive charges introduced by ammonium and pyridinium groups. In the specific case of zwitterionic copolymers Z-4 containing cardanol and zwitterionic groups, Kim et al. [Mhaske et al.  have stum et al.  indicatem et al.  showed tCNSL is a generous raw material with high potential. Generating many synthons in the field of polymers and additives; their application in the field of surfactants is no exception to the rule. From “A Brief Review of Cardanol-Based Surfactant” by Yang et al. in 2014 , the numConsidering a little more closely, the nature of the surfactants obtained or their synthesis, it can be noticed that, for the moment, it is far from an idyllic model. Even if the physicochemical properties  of these surfactants compete with the commercial products currently on sale and in the process of substitution, many of these surfactants are biobased only from the hydrophobic part of their structure provided by the CNSL derivative. Indeed, except for some nonionic structures, where the polar head is a derivative of sugar, most come from compounds that are petrochemicals and/or use toxic/CMR reagents such as sultones or ethylene oxide.Many synthetic pathways also use reagents from conventional chemistry, which are also dangerous for humans and the environment. It would be good to change this—to respect green chemistry. Finally, despite the interest and growing importance of producing non-toxic and ecologically friendly molecules, it is regrettable that little study has been carried out on the possible intrinsic toxicity of synthesized surfactants, despite the known problems of certain structures such as quaternary ammoniums or sulfonates, to name but a few. Some still make the effort to show the biodegradable behavior of their molecule.In the many examples of surfactants synthesized from CNSL present in this review, it can easily be noticed that most of them are cardanol derivatives. Despite the natural biological activity of anacardic acid, it is often little exploited. The reason probably comes from the CNSL extraction method. Anacardic acid, corrosive, is often decarboxylated during extraction to facilitate the recovery of oil from the cashew shell. However, anacardic acid, such as cardol, can be the source of interesting innovations in the field of surfactants, whether in detergent or cosmetic, and will most certainly in the future be more prevalent and used for surfactant synthesis.It should also be noted that the available information on the properties of synthesized surfactant structures is very disparate from one article to another. Even if, in general, the values of CMC and the surface tension of molecules can be found, other information such as Kraft temperature or Cloud Point is regularly missing. Indeed, many of the articles cited in this review, and more often patents, focus on an application of the synthesized surfactant, omitting at the same time other relevant data that it would have been good to share with the scientific community. Nor will we mention here the particular difficulty of finding or calculating hydrophilic-hydrophobic balance (HLB) values—data that are nevertheless useful for industry, which differ according to the nature of polar heads and where, for lack of data on certain chemical structures, it is not even computable.CNSL is, therefore, a good track as synthons for the synthesis of effective surfactants. Much progress has been made over the last 10 years and efforts must be maintained to synthesize and produce non-hazardous surfactants that are the most biobased as possible. Synthesis routes still need to be optimized considering the fundamental principles of green chemistry. The future of this resource will be shaped by simple, inexpensive, and virtuous chemistry, involving the use of all CNSL compounds or even crude oil itself. CNSL provides the hydrophobic part of the surfactant, so it is necessary to imagine, as it is already the case for some nonionic surfactant, the use of bio-based polar heads, which also meet the criteria of non-toxicity. We can then think of sugars, glycerol already used but also some amines, amino acids, acids and diacids, etc.Other interesting perspectives concern CNSL derivatives that are, for the moment, not described as surfactants, but are already synthesized, and whose structure is challenging. Indeed, this is the case of some polyols ,184 deriCNSL, a promising resource, has not yet revealed all these possibilities and therefore remains a relevant molecule to be followed in the synthesis of tomorrow’s bio-based surfactants.