Just thinking you had a better night sleep creates a placebo effect that can improve your cognitive abilities, a new study has found. 
 
 Researchers at Colorado College found students who were told they had a good night’s sleep, even if they did not, performed better on attention and memory skill tests than those who had been informed they had slept badly. 
 
 Research led by Christina Draganich and Colorado College Psychology Professor Kristi Erdal involved 164 students who were told a new technique, which does not actually exist, would be used to measure their sleep pattern from the night before. 
 
 Researchers randomly split participants into “above average” quality sleep and “below average” quality sleep groups. Students in both groups were also given a five minute talk on sleep quality and how important it is for cognitive function. They were told the average proportion of REM sleep a night was between 20 and 20 per cent. 
 
 Participants were then connected to a machine they were told would measure their brainwave frequency and shown spreadsheets and formulas. 
 
 Those in the "above average" sleep quality condition were told by researchers they had spent 28.7 per cent of their total sleep time in REM, whereas those in the "below average" sleep quality condition were informed that they had only spent 16.2 per cent of their time in REM sleep. 
 
 The students who were told they got a good night’s sleep performed significantly better in the Paced Auditory Serial Addition Test, a cognitive exercise which measured their ability to listen and process information. 
 
 The authors say what the students were told about their sleep is known as “placebo sleep.” The effect of that information was a placebo effect, which has to do with the person’s mindset regarding his or her treatment. 
 
 They concluded: “These findings supported the hypothesis that mindset can influence cognitive states in both positive and negative directions, suggesting a means of controlling one's health and cognition.” 
 
 The study Placebo Sleep Affects Cognitive Functioning is published in the Journal of Experimental Psychology: Learning, Memory and Cognition. ||||| The bed must be reserved as a place for sleep and sex only. That was the decree of psychologist Richard Bootzin in his influential 1972 proposal for a "stimulus-control" approach to better sleep. One central tenet was operant conditioning: The bed must be a sanctuary, such that the brain is trained to sleep when it is in the bed. The allowance for sex—which, in its ideal form, is one of the most stimulating things a human body can experience—always seemed to me at odds with the stimulus-control approach. A note to aspiring self-help writers: The book For Better Sleep, Kitchen Sex remains unwritten. Otherwise, though, the idea of stimulus control made sense to a lot of people. It also included advice to avoid bedroom behaviors that abet anxiety, like clock-watching. And Bootzin's approach to insomnia endured, proving itself in several studies. So last year when Charles Czeisler, a professor of sleep medicine at Harvard Medical School, found that around 90 percent of Americans use some kind of electronic device within the hour before bed—and correlated the degree of use with ever-poorer sleep—one of his first theories of the case was overstimulation. That's because, Czeisler and colleagues wrote in the Journal of Clinical Sleep Medicine in December of 2013, "In addition to making phone calls, cell phones now allow the user to instant message, listen to music, send emails, play games, and surf the Internet." So they do. And all of that stimulation, the researchers proposed, may "impede the natural withdrawal of sympathetic nervous system activity necessary for sleep onset." Or, preclude one's ability to chill. To what degree is the light from a device, not the cognitive stimulation it provides, responsible for the known sleep effects of screens? A more vague hypothesis raised by Czeisler at the time was that the detrimental effects on sleep might be due to "light and electromagnetic transmissions from technological devices." Other researchers, too, have lately blamed the light exposure element, which is well understood to influence sleep patterns through photoreceptors in the retina that tell the brain to release the hormone melatonin. It flows forth from the pineal gland into the blood and around the body. Normally, melatonin levels rise before bedtime, peak in the middle of the night, and decrease in the early morning. That is why daily light-dark cycles are important for normal levels of alertness and sleep in most people. Abnormalities in these cycles are the basis for shift-work sleep disorder. But to what degree is the light from a device, not the cognitive stimulation it provides, responsible for the known sleep effects of screens? And is that light worse than, say, the light from a light bulb? In research published today in the journal Proceedings of the National Academy of Sciences, Czeisler and colleagues made an interesting advance in understanding that idea, and just how screens themselves tell our brains to stay awake. It began with the mundane observation that people read to unwind—often at night, often in bed. As far as sleep is concerned, Czeisler wondered, does it matter whether those people read books on iPads, Kindles, or paper? 
 
 Czeisler and colleagues, including lead researcher Anne-Marie Chang, an associate neuroscientist in the division of sleep medicine at Harvard Medical School, recruited a small group of people for an intensive experiment. For two weeks, participants took up residence in a monitoring unit at the clinical investigation center at Boston's Brigham and Women's Hospital. The subject group was only 12 people, but for a trial that requires so much commitment, that is not an unimpressive number. Though it was an enviable situation, in some ways: The people were allotted an idyllic eight hours for sleep, from 10:00 p.m. to 6:00 a.m.—a schedule they kept for three weeks prior, as well, in preparation. They were also allotted four hours of undisturbed reading time each night. The elements of a changing world, from technology and business to politics and culture. 
 
 Read More For five days in a row, the people read either a book or an iPad for four hours prior to sleep. Both were kept at constant, preordained distances from the person's face. Chang and colleagues monitored the people's sleep patterns with electroencephalograms all night. Each person did one stint with the iPad, and one with the book. Before and after each trial period, the people underwent hourly blood tests to paint a day-long picture of just how much melatonin was in their veins at any given time. When subjects read on the iPad as compared to the paper books (hereafter referred to as "books"), the people reported feeling less sleepy at night and less alert the following morning. Of course, this is not a blinded study, the kind with a placebo—the participants could have been biased in reporting how they felt. But, empirically, they also took longer to fall asleep on the iPad nights and spent less time in the REM phase of sleep. And the blood tests showed that on average, the brain's melatonin secretion on those nights was delayed by an hour and a half. Though this experiment dealt exclusively with iPads, the researchers also tested the light-emission patterns of other tablets, as well as phones and laptops. Chang told me they all emitted similar patterns, enriched for short-wavelength blue light, and at a similar intensity. So she would expect similar clinical findings for any such device.
– Got a big day ahead? You're better off thinking you slept well, even if you didn't, a study suggests. Researchers told subjects a normal night of sleep consisted of about 20% to 25% REM sleep. Less than 20%, the subjects heard, meant a worse performance on cognitive tests, while more than 25% meant scoring well on such tests, the Telegraph reports. Researchers duped these subjects into believing that sensors attached to their bodies were tracking their sleep quality. After a night's sleep, some subjects were told they spent 16.2% of the night in REM sleep, while others were informed they'd spent 28.7% of the night in REM. That was all made up, the Smithsonian reports. Next, the subjects took tests involving adding numbers. Subjects who'd been told they'd slept poorly did worse on the tests, reports blogger Eric Horowitz. Those who heard they slept well did better, the Independent reports. In other words, the subjects experienced a "placebo sleep" effect. Indeed, the effect isn't limited to pills: We can get placebo exercise, too, the Smithsonian notes.