The Psychology of Sleep

A close-up photograph of an unmade bed dressed with white bedding in dim lighting. The photo is slightly out of focus. It accompanies a blog post about the psychology of sleep, which discusses the relationship between sleep and personality and offers tips on how to improve sleep.

Our personality can affect our sleep, and our sleep can affect our personality. Given that we spend about one-third of our time asleep, the psychology of sleep may have a greater influence on our well-being than we tend to believe.

Recently on The Science of Personality, Zlatan Krizan, PhD, an award-winning researcher and professor of psychology at Iowa State University, spoke about the psychology of sleep and its relation to personality. How exactly does sleep deprivation affect our physical, mental, and emotional well-being, both personally and professionally?

After experiencing insomnia, Zlatan began to study the neuroscience of sleep. That inspired him to research the intersection of sleep and psychology.

The Psychological Importance of Sleep

Active and rest cycles have always been a universal part of vertebrate consciousness. “Something that perennial must be important. The question is what happens when we don’t do it or we don’t do it well enough,” Zlatan said.

Adults generally need an average of seven to nine hours of sleep per night. Within a sleep episode, we experience repeating 90-minute cycles of rapid eye movement (REM) and non-REM sleep. Sleep quality is complex—and so are sleep problems. Interrupted sleep means not getting continuous sleep. Sleep deprivation or restriction means not getting enough sleep. Total sleep deprivation means not getting any sleep.

“Not everybody’s equally sensitive to the impact of sleep disruption. People are not just different in how much and how they sleep, but they’re also different in how well they can withstand consequences of sleep loss,” he explained. Low resistance to sleeplessness can cause social and cognitive disturbances.

Effects of Sleep Disruption

Zlatan listed four aspects of our lives that are particularly sensitive to sleep quality: (1) alertness, (2) mood, (3) executive function, and (4) physical function. Alertness and attentiveness to our surroundings can suffer under sleep disruption. Motor behavior and reaction time slow down, and we may miss environmental stimuli entirely. A dangerous example would be a sleep-deprived airline pilot failing to respond to or even notice birds on the horizon.

Mood alterations are also a consequence of sleep disruption. Loss of energy or enthusiasm, increased irritability or risk tolerance, and even anger and depression can be provoked by sleep disruption. “Sleepy people, to be exact, get cranky,” Zlatan quipped. He also mentioned that sleep disruption affects executive processes, such as comprehension and memory.

Finally, sleep disruption can affect physical health. The cardiovascular system, immune system, digestive system, and many other critical functions rely on sleep to operate at an optimal level. Long-term shift workers, such as healthcare providers, may become chronically sleep deprived. This places them at greater risk of negative health outcomes, including diabetes, metabolic syndrome, cardiovascular difficulties, and more.

Personality and Sleep

Sleep is dynamic—arguably more so than personality itself. When we consider how personality impacts sleep, we must think about both sleep quality and sleep pressure. Sleep pressure refers to the perceived need to sleep. For example, the night before an important presentation would come with more sleep pressure than an ordinary night. Ironically, excessive sleep pressure can damage sleep quality.

“The logical connection between personality and how people sleep is their emotional functioning,” Zlatan said. “Emotions can impact and undermine sleep.” When people experience stress and negative emotions before bed, they take longer to fall asleep and sleep for a shorter time. But that’s just the tip of the proverbial iceberg when it comes to personality and sleep. Research suggests that specific dimensions of the five-factor model—emotional stability, extraversion, and conscientiousness—affect sleep.

Emotional Stability

Individuals who have higher intensity or higher frequency of negative emotions may have sleep that is more disrupted. Emotional stability, also called neuroticism, concerns feelings that are volatile, anxious, or depressive. People with low emotional stability who experience negative emotions before bed tend to fall asleep later and wake up more during the night, Zlatan pointed out. They may also feel dissatisfied with their sleep, adding to their sleep pressure.

Zlatan shared his own experience with insomnia. While unable to fall asleep, he worried about sleeping enough to be sharp the next day. The additional anxiety about sleep added to his difficulty in sleeping.


People who are high in extraversion report having better sleep. This trend seems to contradict the stereotype of someone with ambition and drive who prides themselves on sleeping very little. It may be that extraverted people tend to exhibit optimism and simply recall sleeping well. Even if this is the case, the positive affect could help lower sleep pressure, which may actually improve sleep. In fact, Zlatan’s next research project focuses on extraversion and sleep quality association.

Zlatan called sleeping less to improve performance a trade-off. Accomplishing additional tasks instead of sleeping can be good, but eventually performance will suffer. Electing to forgo sleep over a long period of time is rarely the best option from a well-being perspective.


Having high conscientiousness, which refers to the tendency to be organized and hardworking, indirectly affects sleep. Conscientious individuals tend to be better at building structure, habit, and routine into their lifestyles, which can provide benefits to sleep. “Conscientious people have much more stable sleep time and wake time,” Zlatan said.

As well as having more consistent sleep, people high in conscientiousness tend to avoid things that harm sleep, such as late-night screen time or alcohol use. “Those indirect pathways in some ways are the most fascinating to explore,” he added.

How to Improve Sleep

Genetics, personality, and other factors largely outside of individual control all affect sleep quality. However, some techniques will help us increase the likelihood of a good night’s sleep. These originate in understanding the circadian rhythm, a 24-hour-long cycle of waking and sleeping.

Consistency in sleep hours, sleep duration, and even mealtimes can support the circadian rhythm and help to prepare the body for sleep many hours before night. Even during sleep deprivation, the circadian rhythm of the body will trigger the wake maintenance zone, which is a brief period in the evening when we feel alert and normal. After we experience this “second wind,” we “crash,” or feel even more tired. Strategic use of wakeful periods can help maximize productivity throughout the day.

Shift workers can protect their circadian rhythms by maintaining consistent habits at intervals of six, 12, or 24 hours whenever possible. Travelers can anticipate and lessen jet lag by deliberately adjusting their circadian rhythms in advance of a time zone change. Insomniacs can lower sleep pressure by tracking their circadian rhythms and compensating for fatigue in healthy ways.

In addition to these higher-level strategies, Zlatan listed some tips that can help people have a better sleep.

  • Breathing – Heart rate and breathing rate are connected; breathing exercises that elongate the exhalation will also slow down the heartbeat and lower stress.
  • Positivity – Practicing gratitude interventions can help to generate positive emotions before sleeping.
  • Planning – A mind dump in the form of a to-do list for tomorrow can address some of the short-term anxieties that can interrupt our attempts to fall asleep.

Oh, and avoiding screens before bed almost goes without saying. “The first thing is to do is to not engage with the algorithms whose sole purpose is to have you not go to sleep,” Zlatan said.

Listen to this conversation in full on episode 95 of The Science of Personality. Never miss an episode by following us anywhere you get podcasts. Cheers, everybody!