A good night’s sleep may seem like a far-fetched dream for many with the demands of living in a 24/7 society. Sleep goes beyond getting simple rest — the brain and body are currently active performing important tasks that help promote both mental and physical health. Proper sleep is known to contribute to feeling better and functioning better, but thinking you got a good night’s rest could mimic that. According to a recent study, people who get placebo sleep — believing they had better sleep — can benefit from enhanced cognitive function.

Although many believe the need for sleep declines with age, the National Sleep Foundation says it is essential for a person’s health and well-being. During sleep, our brains are very active as we pass through the five phases of sleep: stages one, two, three, four, and REM (rapid eye movement) sleep. In REM sleep, breathing becomes more rapid, irregular, and shallow, while the eyes move in various directions, and the limb muscles are temporarily paralyzed. These stages occur in a cycle from stage one to REM sleep, and then proceed to start all over again with stage one. The National Institute of Neurological Disorders and Stroke says we spend almost 50 percent of our total sleep time in stage two sleep, about 20 percent in REM sleep, and the remaining 30 percent in the other stages.

Interruption of these stages, or a poor night’s sleep, can lead to experiencing apathy, slowed speech, flattened emotional responses, impaired memory, and the inability to multitask the next day. However, a team of researchers at Colorado College believe mindset can influence cognitive states in both positive and negative directions, meaning if people think they got a good night’s rest, their brains will work better.

Published in the Journal of Experimental Psychology: Learning, Memory and Cognition, the study led by Christina Draganich and Colorado College Psychology Professor Kristi Erdal, examined how the placebo effect can extend beyond its use in pharmaceutical drugs to other life aspects, such as the effect of sleep on cognitive function. One hundred and sixty-four participants were recruited and told they would undergo a new technique (that doesn’t actually exist) to measure their sleep pattern from the previous night. The volunteers were later randomly split into two groups: “above average” quality sleep and “below average” quality sleep.

The participants were given a five-minute talk on sleep quality and how essential it is for cognitive function. The researchers also told them the average portion of REM sleep a night was 20 percent. After the brief lecture, the volunteers were connected to a machine that would allegedly measure their brainwave frequency, while being shown spreadsheets and formulas. Those in the “above average” sleep quality group were informed they had spent 28.7 percent of their total sleep time in REM, while those in the “below average” group were told they had only spent 16.2 percent of their time in sleep stage, according to The Independent. The groups were given cognitive exercises that measured their ability to listen and process information, along with verbal fluency.

The findings revealed the participants that were told they had below average quality sleep, performed significantly worse on the Paced Auditory Serial Addition Test (PASAT). This exam asked people to put a series of numbers together. There was no correlation found between self-reported sleep quality and PASAT performance. Similarly, on the Controlled Oral Word Association Task (COWAT) test, the researchers found telling people they had below average sleep quality led to an inferior performance, whereas telling them they had above average sleep led to a superior performance. The researchers were surprised assigned sleep quality but not self-reported sleep quality significantly predicted the participants’ scores in several tests like the Digital Span task and the Symbol Digit Modalities test.

“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 researchers concluded.

In a similar study, published in the journal Psychological Science, researchers found the relationship between exercise and health can be moderated by one’s mindset. Hotel housekeepers that were told their work was good exercise, found those workers to score higher on health indicators compared to the group that didn’t think they were getting exercise on the job. Whether the change in physiological health was brought about directly or indirectly, it is clear that health is significantly affected by mind-set,” said Ellen Langer, author of the study and Harvard University psychologist, in a press release. This particular finding highlights thinking you got a work out could actually make you healthier.

Overall, these studies are revealing of the power of the placebo effect. Your mindset can influence cognitive states, meaning if someone tells you a particular treatment will work, it will most likely work. The effect of moderating your mindset could prove valuable when it comes to enhancing your health.


Draganich C and Erdal K. Placebo Sleep Affects Cognitive Functioning. Journal of Experimental Psychology: Learning, Memory and Cognition. 2014.

Crum AJ and Langer EJ. Mind-set matters: exercise and the placebo effect. Psychological Science. 2007.