Couple sleeping
March 03, 2020

Importance of sleep and how to get the most of it


Whether you want to optimize health and performance or beat a health problem, sleep is a key ingredient. With the modern lifestyle and technologies, we are getting less sleep and worse sleep quality—over 35% of US adults get less than seven hours every night1. Since March is sleep awareness month, we explore the ins and outs of better sleep and how infrared sauna sessions can help.

What happens when you sleep?

Sleep isn’t just laying still through the night. Rather, sleep is when your body performs many vital functions as it cycles through different stages, including rapid eye movement (REM), and non-REM N1, N2 and N3 stages.

N1 and N2 are lighter transitional stages between wakefulness and sleep. N3 (Slow Wave Sleep) is the deepest and most restorative sleep where your heartbeat, breathing, and brain waves are at their slowest.

Sleep cycle graphic

Caption: Ideal sleep cycle, where N3 (Non-REM 3) is the deepest sleep and R (REM) is the most active type of sleep.2

REM sleep is paradoxically rather active when your body lacks movement while your brain frequency, breathing, heart rate and blood pressure increases. REM sleep is important for memory formation and emotional processing.3

What makes a great night’s sleep?

According to the National Sleep Foundation,4 a good night of sleep means that:

  • You fall asleep easily, within 15 – 30 minutes
  • Your sleep is uninterrupted, with few or no awakenings throughout the night
  • You achieve all sleep stages and cycle through them naturally
  • You achieve sufficient lengths of deep (16 – 20%) and REM (21 – 30%) sleep of total sleep time of 7 – 9 hours

Most people know their sleep duration but are unaware of their sleep quality, which is best measured with a sleep study. Many consumer devices, such as the Oura ring and Resmed S+, can estimate sleep stages based on heart rates, breathing patterns and movements. In addition, energy levels, alertness, mood, cognitive function, and low resting heart rate are good indicators of sleep quality.

Deep sleep: your most restorative sleep

Deep sleep is when growth hormone, the anti-aging and growth-stimulating hormone, is released the most.5 Your nervous system shifts from fight or flight to rest and digest, so deep sleep helps your nervous system reset from daily stress. Insufficient deep sleep keeps the body stressed, which can increase blood pressure and the risk of stress-related illnesses.7

Deep sleep is when your brain cells get the cleanup they need because the glymphatic system, the brain’s housekeeper, is most active during deep sleep.8

Harmful effects of poor sleep
  1. Increased inflammation and impaired immune function
    Sleep loss increases chronic inflammation, which can worsen pain, allergies and autoimmunity.9 At the same time, sleep deprivation impairs immune function, making you more likely to catch infections and take longer to heal wounds.
  2. Increased hunger, cravings and insulin resistance
    Sleep deprivation increases the hunger hormone, ghrelin and causes resistance to the satiety hormone, leptin.12-14 Sleep deprivation also causes insulin resistance, which may contribute to type II diabetes.15 Therefore, many people have worse cravings and gain weight during periods of sleep deprivation. Poor sleep drives obesity and makes it more difficult to eat healthy, control portions and get in shape.16,17
  3. Increased risk of cardiovascular diseases
    Lack of sleep and sleep disorders are major drivers of cardiovascular diseases due to increased chronic inflammation, stress, insulin resistance, blood pressure and weight gain.18
  4. Hormone imbalances and infertility
    Poor sleep increases the stress hormone, cortisol and thyroid-stimulating hormone.19 In healthy young men, one week of sleeping five hours a night reduced their testosterone levels by 10 – 15%.20 Since testosterone naturally declines by 1 – 2% every year, this reduction is equivalent to 10 – 15 years of aging.

    In premenopausal women, short sleep duration is associated with irregular cycles.21 Women who suffer from polycystic ovarian syndrome are more likely to suffer from sleep disturbances and sleep disorders.22 Overall, sleep problems can throw off hormones and stress out the body, contributing to hormone imbalances and infertility.
  5. Accelerated aging
    Lack of sleep promotes aging by throwing off metabolism and hormone balance, stressing out the body and increasing oxidative stress. People who sleep less have premature shortening of telomeres, suggesting that they age prematurely.23
  6. Poor exercise recovery
    Because sleep deprivation keeps the body stressed and impair immune function, it reduces exercise recovery in all aspects, including diminished muscle strength, muscle growth, and exercise performance in response to training.24-26 Muscles also get repaired during sleep, specifically during stage 3 of your 5 – 6 stage sleep cycle. It’s in this stage that eye and muscle movement stops and the body starts releasing growth hormone to build and repair muscle tissue. But muscle recovery also begins before you even get to sleep. A great muscle recovery program should also include ample time in an infrared sauna, as infrared saunas enhance muscle recovery process by increasing blood circulation, carrying oxygen-rich blood to muscles that have been torn due to exercising.
  7. Worsened mental health  
    Sleep is a neurological process driven by the brain and for the brain. One night of sleep deprivation can worsen mood and emotional response. Poor sleep may increase the risk of developing mental health disorders. Also, disordered sleep patterns are common symptoms of psychiatric and neurological disorders.27 Severe sleep deprivation can lead to hallucinations and psychosis in healthy people.28

One single night without sleep can make the amygdala (the stress and fear memory center in the brain) significantly more reactive,29 which may increase anxiety and inappropriate responses to stress. 

Although coffee may take away the fatigue and make you feel awake, it does not adequately replace sleep because it doesn’t provide the same restoration that your body needs. In addition, caffeine may not restore all deficits in brain function.35

Sleep disorders, such as sleep apnea and restless leg syndrome, also increase the same health risks as sleep deprivation itself. In addition, breathing disruptions during apnea episodes may also cause death and other health problems due to lack of oxygen to the brain.36 Unfortunately, 80% of cases of moderate and severe obstructive sleep apnea remain undiagnosed.37

If you are often tired or struggle with any of the health issues above, consider optimizing sleep and speaking with your doctor about ruling out sleep disorders.

How to optimize sleep naturally

Optimizing sleep quality involves supporting your natural circadian rhythm (body clock) and making sure your sleep pressure is high when it’s bedtime.

Your circadian rhythm helps you sleep at nighttime. The most potent circadian rhythm cue is light exposure, followed by body temperature, mealtimes and other activities.38 Excessive bright artificial light at night can lower sleep quality by increasing your nighttime alertness and reducing melatonin.39 In addition, staying up late and sleeping in can throw off your body clock and make it harder to sleep well in subsequent nights.40 

To promote a healthy circadian rhythm, it is important to be exposed to bright light during the day and reduce blue light at night. Apps like F.lux and blue light blocking glasses can help reduce blue light exposure at night. In addition, it is important to stick to a bedtime routine that involves not eating too late, winding down, and going to bed at the same time every night. Last but not least, ensure that your sleep environment is cool and completely dark.

Many sleep remedies support sleep by promoting relaxation, helping you wind down towards bedtime, such as an infrared sauna session, lavender, passionflower, cannabidiol (CBD) and GABA supplements.41-44

Your sleep pressure is governed by levels of adenosine, inflammation and oxidative stress.45,46 High sleep pressure makes you sleepy and also deepens your sleep. Conversely, sleep reduces the levels of these molecules and makes you more alert. Caffeine makes us more alert by blocking adenosine receptors, but it may worsen sleep.35 As such, taking anti-inflammatory or antioxidants at night may reduce sleep quality.

Physical activity and heat exposure during the day can both promote a healthy circadian rhythm and increase sleep drive. The drop in body temperature afterward reinforces the circadian pattern and promotes relaxation.47 Sauna use, especially infrared sauna, can also elicit similar benefits while relaxing instead of working out. In addition, far infrared therapy may further improve sleep quality by increasing deep sleep in ways that do not involve heat.48,49

Relaxing in gentle heat, like in Sunlighten saunas, can be part of a great bedtime routine that improves sleep quality by promoting relaxation, healthy circadian rhythm and sleep drive.

Learn more about the health benefits of Sunlighten infrared therapy.


1CDC. Data and Statistics – Sleep and Sleep Disorders. National Center for Chronic Disease Prevention and Health Promotion, Division of Population Health (2017) Last accessed: 01/27/2020

2Blume, C., del Giudice, R., Wislowska, M., Lechinger, J. & Schabus, M. Across the consciousness continuum—from unresponsive wakefulness to sleep. Front. Hum. Neurosci. 9, (2015).

3Groch, S., Wilhelm, I., Diekelmann, S. & Born, J. The role of REM sleep in the processing of emotional memories: Evidence from behavior and event-related potentials. Neurobiol. Learn. Mem. 99, 1–9 (2013).

4Ohayon, M. et al. National Sleep Foundation’s sleep quality recommendations: first report. Sleep Heal. 3, 6–19 (2017).

5Van Cauter, E. et al. Reciprocal interactions between the GH axis and sleep. Growth Horm. IGF Res. 14, (2004).

6Brandenberger, G., Ehrhart, J., Piquard, F. & Simon, C. Inverse coupling between ultradian oscillations in delta wave activity and heart rate variability during sleep. Clin. Neurophysiol. 112, 992–6 (2001).

7Tasali, E., Leproult, R., Ehrmann, D. A. & Van Cauter, E. Slow-wave sleep and the risk of type 2 diabetes in humans. Proc. Natl. Acad. Sci. U. S. A. 105, 1044–1049 (2008).

8Hablitz, L. M. et al. Increased glymphatic influx is correlated with high EEG delta power and low heart rate in mice under anesthesia. Sci. Adv. 5, eaav5447 (2019).

9Mullington, J. M., Simpson, N. S., Meier-Ewert, H. K. & Haack, M. Sleep loss and inflammation. Best Practice and Research: Clinical Endocrinology and Metabolism vol. 24 775–784 (2010).

10Irwin, M. R. Sleep and Infectious Disease Risk. Sleep 35, 1025–1026 (2012).

11Smith, T. J. et al. Impact of sleep restriction on local immune response and skin barrier restoration with and without multinutrient nutrition intervention. J. Appl. Physiol. 124, 190–200 (2018).

12Schmid, S. M., Hallschmid, M., Jauch-Chara, K., Born, J. & Schultes, B. A single night of sleep deprivation increases ghrelin levels and feelings of hunger in normal-weight healthy men. J. Sleep Res. 17, 331–334 (2008).

13Taheri, S., Lin, L., Austin, D., Young, T. & Mignot, E. Short sleep duration is associated with reduced leptin, elevated ghrelin, and increased body mass index. PLoS Med. 1, 210–217 (2004).

14Leproult, R. & Van Cauter, E. Role of sleep and sleep loss in hormonal release and metabolism. Endocrine Development vol. 17 11–21 (2009).

15Donga, E. et al. A single night of partial sleep deprivation induces insulin resistance in multiple metabolic pathways in healthy subjects. J. Clin. Endocrinol. Metab. 95, 2963–2968 (2010).

16Gangwisch, J. E., Malaspina, D., Boden-Albala, B. & Heymsfield, S. B. Inadequate sleep as a risk factor for obesity: Analyses of the NHANES I. Sleep 28, 1289–1296 (2005).

17Beccuti, G. & Pannain, S. Sleep and obesity. Current Opinion in Clinical Nutrition and Metabolic Care vol. 14 402–412 (2011).

18Yuan, R., Wang, J. & Guo, L. li. The Effect of Sleep Deprivation on Coronary Heart Disease. Chinese Medical Sciences Journal vol. 31 247–253 (2016).

19Kim, T. W., Jeong, J. H. & Hong, S. C. The impact of sleep and circadian disturbance on hormones and metabolism. International Journal of Endocrinology vol. 2015 (2015).

20Leproult, R. & Van Cauter, E. Effect of 1 week of sleep restriction on testosterone levels in young healthy men. JAMA – Journal of the American Medical Association vol. 305 2173–2174 (2011).

21Baker, F. C. & Lee, K. A. Menstrual Cycle Effects on Sleep. Sleep Medicine Clinics vol. 13 283–294 (2018).

22Fernandez, R. C. et al. Sleep disturbances in women with polycystic ovary syndrome: prevalence, pathophysiology, impact and management strategies. Nat. Sci. Sleep 10, 45–64 (2018).

23Teo, J. X. et al. Digital phenotyping by consumer wearables identifies sleep-associated markers of cardiovascular disease risk and biological aging. Commun. Biol. 2, (2019).

24McMurray, R. G. & Brown, C. F. The effect of sleep loss on high intensity exercise and recovery. Aviat. Sp. Environ. Med. 55, 1031–1035 (1984).

25Buchmann, N. et al. Schlaf, Muskelmasse und Muskelfunktion im Alter. Dtsch. Arztebl. Int. 113, 253–260 (2016).

26Vitale, K. C., Owens, R., Hopkins, S. R. & Malhotra, A. Sleep Hygiene for Optimizing Recovery in Athletes: Review and Recommendations. Int. J. Sports Med. 40, 535–543 (2019).

27Anderson, K. N. & Bradley, A. J. Sleep disturbance in mental health problems and neurodegenerative disease. Nature and Science of Sleep vol. 5 61–75 (2013).

28Waters, F., Chiu, V., Atkinson, A. & Blom, J. D. Severe sleep deprivation causes hallucinations and a gradual progression toward psychosis with increasing time awake. Frontiers in Psychiatry vol. 9 (2018).

29Yoo, S. S., Gujar, N., Hu, P., Jolesz, F. A. & Walker, M. P. The human emotional brain without sleep – a prefrontal amygdala disconnect. Current Biology vol. 17 (2007).

30Alhola, P. & Polo-Kantola, P. Sleep deprivation: Impact on cognitive performance. Neuropsychiatric Disease and Treatment vol. 3 553–567 (2007).

31Uehli, K. et al. Sleep problems and work injuries: A systematic review and meta-analysis. Sleep Medicine Reviews vol. 18 61–73 (2014).

32American Safety Council. 10 Sleep Deprivation Hazards on the Worksite | OSHA 10. Last accessed: 01/27/2020

33Tefft, B. C. Acute sleep deprivation and culpable motor vehicle crash involvement. Sleep 41, (2018).

34NHTSA. Drowsy Driving. NHTSA (2017). Last accessed: 01/27/2020

35O’callaghan, F., Muurlink, O. & Reid, N. Effects of caffeine on sleep quality and daytime functioning. Risk Management and Healthcare Policy vol. 11 263–271 (2018).

36Sforza, E. & Roche, F. Chronic intermittent hypoxia and obstructive sleep apnea: an experimental and clinical approach. Hypoxia 99 (2016) doi:10.2147/hp.s103091.

37American Sleep Apnea Association. Sleep Apnea Information for Clinicians – Sleep Apnea. Last accessed: 01/27/2020

38Mistlberger, R. E. & Skene, D. J. Social influences on mammalian circadian rhythms: animal and human studies. Biol. Rev. 79, 533–556 (2004).

39Kozaki, T., Kubokawa, A., Taketomi, R. & Hatae, K. Effects of day-time exposure to different light intensities on light-induced melatonin suppression at night. J. Physiol. Anthropol. 34, 27 (2015).

40Sűdy, Á. R., Ella, K., Bódizs, R. & Káldi, K. Association of Social Jetlag With Sleep Quality and Autonomic Cardiac Control During Sleep in Young Healthy Men. Front. Neurosci. 13, (2019).

41López, V., Nielsen, B., Solas, M., Ramírez, M. J. & Jäger, A. K. Exploring pharmacological mechanisms of lavender (Lavandula angustifolia) essential oil on central nervous system targets. Front. Pharmacol. 8, (2017).

42Elsas, S. M. et al. Passiflora incarnata L. (Passionflower) extracts elicit GABA currents in hippocampal neurons in vitro, and show anxiogenic and anticonvulsant effects in vivo, varying with extraction method. Phytomedicine 17, 940–949 (2010).

43Babson, K. A., Sottile, J. & Morabito, D. Cannabis, Cannabinoids, and Sleep: a Review of the Literature. Current Psychiatry Reports vol. 19 (2017).

44Boonstra, E. et al. Neurotransmitters as food supplements: The effects of GABA on brain and behavior. Frontiers in Psychology vol. 6 (2015).

45Krueger, J. The Role of Cytokines in Sleep Regulation. Curr. Pharm. Des. 14, 3408–3416 (2008).

46Kimura, M., Kapás, L. & Krueger, J. M. Oxidized glutathione promotes sleep in rabbits. Brain Res. Bull. 45, 545–8 (1998).

47Zalewski, P. et al. Cardiovascular and Thermal Response to Dry-Sauna Exposure in Healthy Subjects. Physiol. J. 2014, 1–10 (2014).

48Inoué, S. & Kabaya, M. Biological activities caused by far-infrared radiation. International Journal of Biometeorology vol. 33 145–150 (1989).

49Honda, K. & Inoué, S. Sleep-enhancing effects of far-infrared radiation in rats. Int. J. Biometeorol. 32, 92–4 (1988).

profile picture

WRITTEN BY: Sunlighten

Shining light on infrared technology, Sunlighten® is the #1 choice for personalized infrared light treatments. Since 1999, we have been committed to innovating wellness products and services that empower our customers to improve their quality of life. Our patented SoloCarbon® technology rejuvenates the body by delivering the highest dose of infrared energy to the body - proven up to 99% effective. Our technological innovations are fueled by our passion to make a difference. And we are building a global community of businesses, consumers, and trusted experts to support each other along the way and make the world a healthier, happier place.

Sunlighten saunas are not a medical device as defined by Section 201(h) of the Food, Drug & Cosmetic Act. Sunlighten provides general information relating to various medical conditions for informational purposes only and is not meant to be a substitute for advice provided by a doctor or other qualified health care professional. Please consult with your physician regarding diagnosis or treatment.