The International Classification of<unk>  Disorders classifies<unk>  as a type of<unk>  dyssomnia. Although studies suggest that 3% of the adult population suffers from a<unk> , many people are often misdiagnosed with insomnia instead of a<unk> . Of adults diagnosed with<unk>  disorders, an estimated 10% have a<unk>  and of adolescents with<unk>  disorders, an estimated 16% may have a<unk> . Patients diagnosed with<unk> s typically express a pattern of disturbed<unk> , whether that be excessive<unk>  that intrudes on working schedules and daily functions, or insomnia at desired times of<unk> . Note that having a preference for extreme early or late wake times are not related to a<unk>  diagnosis. There must be distinct impairment of biological<unk> s that affects the person's desired work and daily behavior. For a<unk>  diagnosis, a<unk>  specialist gathers the history of a patient's<unk>  and wake habits, body temperature patterns, and dim-light melatonin onset (DLMO). Gathering this data gives insight into the patient's current schedule, as well as the physiological phase markers of the patient's biological clock. The start of the<unk>  diagnostic process is a thorough<unk>  history assessment. A standard questionnaire is used to record the<unk>  habits of the patient, including typical bedtime,<unk>  duration,<unk>  latency, and instances of waking up. The professional will further inquire about other external factors that may impact<unk> . Prescription drugs that treat mood disorders like tricyclic antidepressants, selective serotonin reuptake inhibitors and other antidepressants are associated with abnormal<unk>  behaviors. Other daily habits like work schedule and timing of exercise are also recorded—because they may impact an individual's<unk>  and wake patterns. To measure<unk>  variables candidly, patients wear actigraphy watches that record<unk>  onset, wake time, and many other physiological variables. Patients are similarly asked to self-report their<unk>  habits with a week-long<unk>  diary to document when they go to bed, when they wake up, etc. to supplement the actigraphy data. Collecting this data allows<unk>  professionals to carefully document and measure patient's<unk>  habits and confirm patterns described in their<unk>  history. Other additional ways to classify the nature of a patient's<unk>  and biological clock are the morningness-eveningness questionnaire (MEQ) and the Munich ChronoType Questionnaire, both of which have fairly strong correlations with accurately reporting phase advanced or delayed<unk> . Questionnaires like the Pittsburgh<unk>  Quality Index (PSQI) and the Insomnia Severity Index (ISI) help gauge the severity of<unk>  disruption. Specifically, these questionnaires can help the professional assess the patient's problems with<unk>  latency, undesired early-morning wakefulness, and problems with falling or staying<unk> . Tayside children's<unk>  questionnaire is a ten-item questionnaire for<unk>  disorders in children aged between one and five years old.
Circadian rhythm sleep disorder
Non-24-hour sleep–wake disorder
Shift work sleep disorder
Delayed sleep phase disorder
Advanced sleep phase disorder
Sleep disorder
Rapid eye movement sleep behavior disorder
Sleep state misperception