Sleep 101: Common Questions About Understanding and Improving Sleep

woman sleeping

This article explains what research says about sleep and improving sleep.

Sleep is a bodily function critical for our physical and psychological well-being. In fact we spend nearly one-third of our lives sleeping or attempting to sleep (Aminoff et al., 2011). 

Despite the importance of sleep, Americans do not get enough sleep on a regular basis (1 in 3 Adults Don’t Get Enough Sleep | CDC Online Newsroom | CDC 2016). 

Sleep deprivation is often connected with several physical and mental disturbances, which may lead to other health concerns. 

Yet while poor sleep may be a nationwide concern you can improve your quality and duration of sleep with a few simple practices and lifestyle changes. 

What Is Sleep?

Sleep is a unique bodily state of rest. While sleep may appear to be an inactive state, our brain functions can be even more active during some parts of sleep than when we are awake (What Is Sleep? | Healthy Sleep, n.d.). Sleep impacts every type of tissue in the body, including your brain, heart, lungs, immune system, and more (Brain Basics: Understanding Sleep | National Institute of Neurological Disorders and Stroke, 2019). 

Sleep includes different depths and types throughout the course of the night. The process is dynamic and researchers are only recently beginning to understand more about this complex behavior. 

Sleep can be divided into 2 broad phases:

  • NonRapid Eye Movement (Non-REM): Non-REM sleep occurs after a transitional period of deep sleep. The body’s temperature drops,  heart rates lower, and the brain uses less energy. 

There are multiple stages of Non-REM sleep in your sleep cycle (Suni & Vyas, 2020). 

  • Stage 1: 1-5 minutes. The body and brain activities begin to slow; this is the stage of “falling asleep.” 
  • Stage 2: 10-60 minutes. Subdued bodily state, where muscles relax and your heart rate slows. Brain waves also slow and eye movement ceases. This stage often makes up about half of the sleep throughout the night. 
  • Stage 3: Slow-wave or deep sleep, lasts 20-40 minutes at a time. It is very difficult to wake someone during this phase of sleep, as the body is very relaxed. The brain shows delta waves, and this stage is known for restoration, recovery, and growth. 
  • Rapid Eye Movement (REM): Also known as paradoxical sleep, REM happens after stage 3 of Non-REM sleep. It is the main occasion for vivid dreams and is associated with desynchronized brain waves and rapid-eye-movement. 

What Is Dreaming?

Vivid dreams are most closely associated with REM sleep since brain activity picks up during this time (Suni & Vyas, 2020).  Dreams appear as imaginative stories and images that can include every sense, with the content and style of dreams varying from person to person. For example, it’s more common for blind people to have dreams with more sound, taste, and smell components (Meaidi et al., 2014). 

While dream content is incredibly diverse, some of the most common characteristics include:

  • First-person perspective
  • Incoherent or illogical content 
  • The dreamer interacting with other people, and other people interacting with each other 
  • Strong emotional sensations
  • Incorporated elements of waking life

Yet while we dream for an average of 2 hours per night, most dreams will be forgotten by the time you wake up. (Brain Basics: Understanding Sleep | National Institute of Neurological Disorders and Stroke, 2019). 

The purpose of dreams is not completely known, but many modern scientists believe that dreams help us process events and emotions and may possibly play a role in memory formation (Rasch & Born, 2013). Several animal studies have also shown a link between dreams and memory. 

What Is Dream Analysis?

Dream analysis, or dream interpretation, is the process of finding the meanings of dreams. Psychoanalysts such as Sigmund Freud have suggested that dreams are a portal to our unconscious mind, and thus that they have hidden meaning (Zhang & Guo, 2018). Another famous psychologist, Carl Jung, proposed that dreams help us process daily events and help us realize things about ourselves we did not yet know. 

However, modern researchers aren’t entirely sure of the role of dreams and have many different theories. Some of these theories include:

  • Threat simulation: Dreams may be a way to confront emotional trauma and turmoil in your life. Specifically, dreams may simulate threatening situations and help you safely handle them, to make you feel safer when awake. A 2009 study found that children who experienced trauma had more threatening dreams, which they may have used to practice threat simulation (Valli & Revonsuo, 2009). 
  • Emotional regulation: Unpleasant emotions from daily life, like guilt, anxiety may show up in dreams to give us a chance to resolve these feelings. Interestingly, research has found that the parts of the brain ( the amygdala) that regulate emotions and memory are active during sleep (Brain Basics: Understanding Sleep | National Institute of Neurological Disorders and Stroke, 2019). 
  • Memory formation: Many researchers believe one purpose of dreams is memory consolidation. There are several potential mechanisms for how dreams help you store important memories and things you’ve learned, get rid of unimportant memories, and sort through complicated thoughts and feelings (Payne & Nadel, 2004).
  • Creativity: Dreams hold important potential for inspiring creativity.  A study on college students found that dreams stimulated waking-life creativity (Schredl & Erlacher, 2007). 

Why Do We Need Sleep?

Sleep is critical for our overall health. We need sleep for a variety of key reasons. 

Sleep allows your body and mind to recharge, and without it, the brain cannot function properly. During sleep, the brain forms new pathways and processes information (Sophia, 2016). Because of this, sleep is essential for memory consolidation and prioritizing important content.  

During rest, the brain is overseeing a variety of biological upkeep and preparation for the next day. For example, those who sleep enough tend to finish tasks quicker, demonstrate better reaction times, and make fewer mistakes (Sophia, 2016). 

Physical health also relies on sleep. During sleep, our cells repair, including cells in the cardiovascular system (Sophia, 2016). Sleeping also helps maintain hormonal balance, regulate hunger and promote growth. Because of this, sleep is vital for growth and development, including muscle mass development. Our immune system also depends on sleep, and sufficient sleep is required for fighting infection (Sophia, 2016). 

The Relationship Between Sleep and Mental Health

As mentioned, sleep is imperative for brain function. Thus, it plays a significant role in mental health. This relationship is dual-sided however, as mental health can also impact sleep.

Sleep is closely connected to mental health and research has demonstrated links between sleep patterns and depression, anxiety, bipolar disorder, and other conditions. A recent sleep study involving over 250 million participants stated that nearly half of the total participants that reported having trouble initiating or staying asleep, waking early, or experienced nonrestorative sleep also suffered from mental health disorders (Ohayon & Roth, 2001). 

One study that examined the connection between sleep and anxiety found that sleep issues were a predictor for generalized anxiety disorder in adolescents between ages 9 and 16 (Shanahan et al., 2014). Lack of sleep can also lead to increased distress and anxiety in healthy adults. 

While sleep can contribute to the development of certain mental health issues, psychological conditions may also negatively affect sleep. According to the Sleep Foundation, “Mental health disorders tend to make it harder to sleep well” (Suni, 2020).

How Much Sleep Do You Need?

How much sleep you need depends on a myriad of factors including your age, activity level, and genetic makeup. It is often stated that the average person should aim for 8 hours of sleep each night and this adage may be rooted in science. A 2018 study examining a global sample of over 10,000 individuals found that the average person’s cognitive performance dropped when they had under 7 hours of sleep per night. Interestingly, the study also found that the findings held true across all adult age groups (Wild et al., 2018). 

On the other hand, a 2018 narrative review on sleep argues that “a generally valid assumption is that individuals obtain the right amount of sleep if they wake up feeling well-rested and perform well during the day” (Chaput et al., 2018). 

In other words, the ideal sleep time varies from person to person. There’s no set number of the ideal sleep time, but it’s important to focus on improving sleep quality and duration for overall health. 

How Much Deep Sleep Do You Need?

In addition to the quantity of sleep, quality also matters. Significant regeneration is believed to occur during deep sleep – the same stage that tends to be most impacted when we don’t sleep well. 

Much like overall sleep, the amount of deep sleep you need varies based on several factors. Younger people require more deep sleep to promote growth and development.

You spend roughly 75% of your night in non-REM sleep and the other 25% in REM sleep. Of this, around 13% to 23% of your total sleep is deep sleep (Institute of Medicine (US) Committee on Sleep Medicine and Research, 2006). Therefore, the average adult should get approximately 1 to 2 hours of deep sleep per the recommended 7 to 8 hours of overall sleep.

Deep sleep decreases with age (Li et al., 2018). Research shows that if you’re under age 30, you may get two hours of deep sleep each night. If you’re over age 65, you may only get a half-hour of deep sleep each night, or none at all.

Is Too Much Sleep Bad?

The negative impact of sleep deprivation is well-studied, but many wonder if you can sleep too much. In short, yes you can get too much sleep. Oversleeping is associated with a greater likelihood of psychiatric issues and a greater body mass index (Léger et al., 2014). 

Oversleeping could also be a sign of underlying conditions you may not be aware of. A study of adults found those who sleep over 10 hours reported worse overall mental health (however a causal relationship between oversleeping and mental health was undetermined) (Malhotra et al., 2019). While oversleeping could contribute to mental health conditions, the presence of mental health conditions may also be causing someone to oversleep. 

Therefore, people who require significantly more than the average of 7-9 hours per night may have another underlying health issue. If you struggle with oversleeping or needing excessive sleep to feel rested, then you may want to consider contacting a medical professional.

I Can’t Stay Asleep at Night

Struggling to stay asleep is a common sleep problem that people face. Roughly 30% of the adult U.S. population suffers from insomnia, and 10% suffers from chronic insomnia (Bhaskar et al., 2016). Unfortunately, insomnia is a fairly common problem that can go undiagnosed. 

Why Can’t I Sleep?

There are many reasons why a person may struggle with sleep. According to Harvard Health, some of the most common reasons for sleep disruption include (Harvard Health, 2014):

  • Sleep apnea
  • Chronic pain 
  • Restless leg syndrome
  • Poor sleep habits
  • Stress
  • Caffeine consumption 

Some medications may also affect your sleep including antidepressants, mood stabilizers, stimulants for ADHD, high blood pressure medications, etc. Always ask about potential side effects of medications, and pay attention to your sleep upon transitioning to any new medications. 

What To Do If You Can’t Sleep

Struggling with lack of sleep can be extremely frustrating. Even if other mental or physical conditions are impacting your sleep, there are strategies you can use to improve sleep. Here are some habits that might help with falling asleep:

  • Start by setting a regular sleep schedule. Even if you’re struggling to fall asleep, going to bed and waking up at the same time every day will program your body and mind into a state of relaxation during those hours.
  • Having a peaceful sleep environment helps promote sleep. Attempting to sleep in too hot of a room can lead to interrupted deep sleep and REM sleep (Okamoto-Mizuno & Mizuno, 2012). Temperature, lighting, and noise should be controlled so your bedroom environment helps you fall asleep. Aim for a room temperature of 60 to 67 degrees Fahrenheit. 
  • Exercising regularly helps regulate sleep. According to Charlene Gamaldo, M.D., medical director of Johns Hopkins Center for Sleep at Howard County General Hospital, “we have solid evidence that exercise does, in fact, help you fall asleep more quickly and improves sleep quality” (Exercising for Better Sleep | Johns Hopkins Medicine, n.d.). Experiment with exercise at different times of the day to find a time that works best for you. 
  • Cut down on caffeine and/or nicotine if you use them. Caffeine that is consumed up to 6 hours before bed still disrupts sleep (Drake et al., 2013). Nicotine is a stimulant and can make it harder to fall asleep and cause frequent disruptions during sleep.
  • De-stress. Stress is associated with difficulty falling asleep as well as disrupted sleep architecture (Kim & Dimsdale, 2007) Implementing relaxation techniques can help you relieve stress and calm down before bed. Taking a hot bath, listening to soft music, or doing some gentle yoga are some ways you can relax your mind and body. 


Getting enough sleep is essential for helping a person maintain optimal health and wellbeing. When it comes to overall better health, sleep is as vital as regular exercise and eating a balanced diet. Modern-day living in the United States and many other countries do not always embrace the necessity for adequate rest, yet it is important that people make an effort to get enough sleep regularly.

Sleep deprivation is linked to poorer mental and physical health, but the relationship is often bi-directional. Even so, understanding what exactly sleep is, its relationship to mental health, and good sleep habits will help you improve your sleep.


The following material is provided for informational purposes only and is not designed to prescribe, diagnose, or treat any physical or mental illness. None of the information presented here should be treated as medical or professional advice. 


1 in 3 adults don’t get enough sleep | CDC Online Newsroom | CDC. (2016, January 1). CDC; U.S Department of Health and Human Services. https://www.cdc.gov/media/releases/2016/p0215-enough-sleep.html

Aminoff, M. J., Boller, F., & Swaab, D. F. (2011). We spend about one-third of our life either sleeping or attempting to do so. In Handbook of Clinical Neurology (p. vii). Elsevier. http://dx.doi.org/10.1016/B978-0-444-52006-7.00047-2

APA Dictionary of Psychology. (n.d.). APA Dictionary of Psychology; American Psychological Association. Retrieved August 18, 2021, from https://dictionary.apa.org/dream-analysis

Bhaskar, S., Hemavathy, D., & Prasad, S. (2016). Prevalence of chronic insomnia in adult patients and its correlation with medical comorbidities. Journal of Family Medicine and Primary Care, 4, 780. https://doi.org/10.4103/2249-4863.201153

Brain Basics: Understanding Sleep | National Institute of Neurological Disorders and Stroke. (2019, August 13). National Institute of Neurological Disorders and Stroke | National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-Sleep

Chaput, J.-P., Dutil, C., & Sampasa-Kanyinga, H. (2018). Sleeping hours: what is the ideal number and how does age impact this? Nature and Science of Sleep, 421–430. https://doi.org/10.2147/nss.s163071

Drake, C., Roehrs, T., Shambroom, J., & Roth, T. (2013). Caffeine Effects on Sleep Taken 0, 3, or 6 Hours before Going to Bed. Journal of Clinical Sleep Medicine, 11, 1195–1200. https://doi.org/10.5664/jcsm.3170

Exercising for Better Sleep | Johns Hopkins Medicine. (n.d.). Johns Hopkins Medicine, Based in Baltimore, Maryland. Retrieved August 18, 2021, from https://www.hopkinsmedicine.org/health/wellness-and-prevention/exercising-for-better-sleep

Ford, D. E. (1989). Epidemiologic study of sleep disturbances and psychiatric disorders. An opportunity for prevention? JAMA: The Journal of the American Medical Association, 11, 1479–1484. https://doi.org/10.1001/jama.262.11.1479

Harvard Health . (2014, January 10). 8 reasons why you’re not sleeping – Harvard Health. Harvard Health. https://www.health.harvard.edu/sleep/8-reasons-why-youre-not-sleeping

Institute of Medicine (US) Committee on Sleep Medicine and Research. (2006). Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem (H. Colten & B. Altevogt, Eds.; p. 2). Sleep Physiology .

Kim, E.-J., & Dimsdale, J. E. (2007). The Effect of Psychosocial Stress on Sleep: A Review of Polysomnographic Evidence. Behavioral Sleep Medicine, 4, 256–278. https://doi.org/10.1080/15402000701557383

Léger, D., Beck, F., Richard, J.-B., Sauvet, F., & Faraut, B. (2014). The Risks of Sleeping “Too Much”. Survey of a National Representative Sample of 24671 Adults (INPES Health Barometer). PLoS ONE, 9, e106950. https://doi.org/10.1371/journal.pone.0106950

Li, J., Vitiello, M. V., & Gooneratne, N. S. (2018). Sleep in Normal Aging. Sleep Medicine Clinics, 1, 1–11. https://doi.org/10.1016/j.jsmc.2017.09.001

Malhotra, A., Shapiro, C., Pepin, J.-L., Hedner, J., Ahmed, M., Foldvary-Schaefer, N., Strollo, P. J., Mayer, G., Sarmiento, K., Baladi, M., Chandler, P., Lee, L., & Schwab, R. (2019). Long-term study of the safety and maintenance of efficacy of solriamfetol (JZP-110) in the treatment of excessive sleepiness in participants with narcolepsy or obstructive sleep apnea. Sleep, 2. https://doi.org/10.1093/sleep/zsz220

Meaidi, A., Jennum, P., Ptito, M., & Kupers, R. (2014). The sensory construction of dreams and nightmare frequency in congenitally blind and late blind individuals. Sleep Medicine, 5, 586–595. https://doi.org/10.1016/j.sleep.2013.12.008

Ohayon, M. M., & Roth, T. (2001). What are the contributing factors for insomnia in the general population? Journal of Psychosomatic Research, 6, 745–755. https://doi.org/10.1016/s0022-3999(01)00285-9

Okamoto-Mizuno, K., & Mizuno, K. (2012). Effects of thermal environment on sleep and circadian rhythm. Journal of Physiological Anthropology, 1. https://doi.org/10.1186/1880-6805-31-14

Payne, J. D., & Nadel, L. (2004). Sleep, dreams, and memory consolidation: The role of the stress hormone cortisol. Learning & Memory, 6, 671–678. https://doi.org/10.1101/lm.77104

Rasch, B., & Born, J. (2013). About Sleep’s Role in Memory. Physiological Reviews, 2, 681–766. https://doi.org/10.1152/physrev.00032.2012

Schredl, M., & Erlacher, D. (2007). Self-Reported Effects of Dreams on Waking-Life Creativity: An Empirical Study. The Journal of Psychology, 1, 35–46. https://doi.org/10.3200/jrlp.141.1.35-46

Shanahan, L., Copeland, W. E., Angold, A., Bondy, C. L., & Costello, E. J. (2014). Sleep Problems Predict and Are Predicted by Generalized Anxiety/Depression and Oppositional Defiant Disorder. Journal of the American Academy of Child & Adolescent Psychiatry, 5, 550–558. https://doi.org/10.1016/j.jaac.2013.12.029

Sophia, Y. S., B. Pharm. Reviewed. (2016, March 6). Function of Sleep. News-Medical.Net; News-Medical. https://www.news-medical.net/health/Function-of-Sleep.aspx#:~:text=Sleep%20plays%20an%20important%20role,and%20aid%20in%20making%20decisions.

Suni, E. (2020, September 18). Mental Health and Sleep | Sleep Foundation (A. Dimitriu, Ed.). Sleep Foundation. https://www.sleepfoundation.org/mental-health

Suni, E., & Vyas, Dr. N. (2020, August 14). Stages of Sleep – Sleep Foundation. Sleep Foundation. https://www.sleepfoundation.org/how-sleep-works/stages-of-sleep

Valli, K., & Revonsuo, A. (2009). The threat simulation theory in light of recent empirical evidence: a review. American Journal of Psychiatry. https://doi.org/19353929

What is Sleep? | Healthy Sleep. (n.d.). Healthy Sleep; Division of Sleep Medicine at Harvard Medical School. Retrieved August 18, 2021, from https://healthysleep.med.harvard.edu/healthy/science/what

Wild, C. J., Nichols, E. S., Battista, M. E., Stojanoski, B., & Owen, A. M. (2018). Dissociable effects of self-reported daily sleep duration on high-level cognitive abilities. Sleep, 12. https://doi.org/10.1093/sleep/zsy182

Zhang, W., & Guo, B. (2018). Freud’s Dream Interpretation: A Different Perspective Based on the Self-Organization Theory of Dreaming. Frontiers in Psychology. https://doi.org/10.3389/fpsyg.2018.01553

Looking for more great content on mental health and psychedelics?

Discover inspiring conversations, beautiful music, and educational content on the Mindleap app.

stay connected with us Join our newsletter

Get a weekly pulse on new content we're releasing, including meditation and interviews with world-class researchers and practitioners, learn about new specialists, and read about what's making headlines in inner wellness and psychedelic.