Q: How important is sleep?
A: Sleep is incredibly important, and can be considered crucial alongside diet and exercise. Proper sleep habits help sustain many biological processes, and bad sleep can cause these processes to be suboptimal or even malfunction.
Read full answer to "How important is sleep?"
Cortisol is the hormone that mediates waking up and a variety of catabolic (tissue breakdown) reactions; it isn't bad in any way, but many people with elevated cortisol could suffer pathology from it. In these scenarios, it is nice to lower cortisol and supplementation may be effective.
Our evidence based analysis features 54 unique references to scientific papers.
Follow this Page for updates
Q: How important is sleep?
The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what supplements affect cortisol
|Grade||Level of Evidence|
|Robust research conducted with repeated double-blind clinical trials|
|Multiple studies where at least two are double-blind and placebo controlled|
|Single double-blind study or multiple cohort studies|
|Uncontrolled or observational studies only|
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
All comparative evidence is now gathered in our A-to-Z Supplement Reference.
The evidence for each separate supplement is still freely available here.
|Eurycoma Longifolia Jack|
|Rose Essential Oil|
|Branched Chain Amino Acids|
|Vitamin B3 (Niacin)|
Via HEM and FAQ:
- Yi S, et al. Short sleep duration in association with CT-scanned abdominal fat areas: the Hitachi Health Study. Int J Obes (Lond). (2012)
- Park SE, et al. The association between sleep duration and general and abdominal obesity in Koreans: data from the Korean National Health and Nutrition Examination Survey, 2001 and 2005. Obesity (Silver Spring). (2009)
- Hairston KG, et al. Sleep duration and five-year abdominal fat accumulation in a minority cohort: the IRAS family study. Sleep. (2010)
- Watson NF, et al. Sleep duration and body mass index in twins: a gene-environment interaction. Sleep. (2012)
- Di Milia L, Vandelanotte C, Duncan MJ. The association between short sleep and obesity after controlling for demographic, lifestyle, work and health related factors. Sleep Med. (2013)
- Nedeltcheva AV, et al. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. (2010)
- Benedict C, et al. Acute Sleep Deprivation Enhances the Brain's Response to Hedonic Food Stimuli: An fMRI Study. J Clin Endocrinol Metab. (2012)
- St-Onge MP, et al. Sleep restriction leads to increased activation of brain regions sensitive to food stimuli. Am J Clin Nutr. (2012)
- Bosy-Westphal A, et al. Influence of partial sleep deprivation on energy balance and insulin sensitivity in healthy women. Obes Facts. (2008)
- Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on physiological rhythms. Rev Neurol (Paris). (2003)
- Lemola S, et al. Optimism and Self-Esteem Are Related to Sleep. Results from a Large Community-Based Sample. Int J Behav Med. (2012)
- Sio UN, Monaghan P, Ormerod T. Sleep on it, but only if it is difficult: Effects of sleep on problem solving. Mem Cognit. (2012)
- Knutson KL. Sleep duration and cardiometabolic risk: a review of the epidemiologic evidence. Best Pract Res Clin Endocrinol Metab. (2010)
- Choi JK, et al. Association between short sleep duration and high incidence of metabolic syndrome in midlife women. Tohoku J Exp Med. (2011)
- Najafian J, et al. Association between sleep duration and metabolic syndrome in a population-based study: Isfahan Healthy Heart Program. J Res Med Sci. (2011)
- Cappuccio FP, et al. Quantity and quality of sleep and incidence of type 2 diabetes: a systematic review and meta-analysis. Diabetes Care. (2010)
- Beihl DA, Liese AD, Haffner SM. Sleep duration as a risk factor for incident type 2 diabetes in a multiethnic cohort. Ann Epidemiol. (2009)
- Chaput JP, et al. Sleep duration as a risk factor for the development of type 2 diabetes or impaired glucose tolerance: analyses of the Quebec Family Study. Sleep Med. (2009)
- Chao CY, et al. Sleep duration is a potential risk factor for newly diagnosed type 2 diabetes mellitus. Metabolism. (2011)
- Broussard JL, et al. Impaired insulin signaling in human adipocytes after experimental sleep restriction: a randomized, crossover study. Ann Intern Med. (2012)
- Robertson MD, et al. Effects of three weeks of mild sleep restriction implemented in the home environment on multiple metabolic and endocrine markers in healthy young men. Metabolism. (2013)
- Impact of Five Nights of Sleep Restriction on Glucose Metabolism, Leptin and Testosterone in Young Adult Men.
- Buxton OM, et al. Sleep restriction for 1 week reduces insulin sensitivity in healthy men. Diabetes. (2010)
- Donga E, et al. A single night of partial sleep deprivation induces insulin resistance in multiple metabolic pathways in healthy subjects. J Clin Endocrinol Metab. (2010)
- Penev PD. Association between sleep and morning testosterone levels in older men. Sleep. (2007)
- Luboshitzky R, Shen-Orr Z, Herer P. Middle-aged men secrete less testosterone at night than young healthy men. J Clin Endocrinol Metab. (2003)
- Randler C, et al. Chronotype but not sleep length is related to salivary testosterone in young adult men. Psychoneuroendocrinology. (2012)
- Validation of the full and reduced Composite Scale of Morningness.
- An actigraphic validation study of seven morningness-eveningness inventories.
- Roenneberg T, et al. A marker for the end of adolescence. Curr Biol. (2004)
- Leproult R, Van Cauter E. Effect of 1 week of sleep restriction on testosterone levels in young healthy men. JAMA. (2011)
- Cortés-Gallegos V, et al. Sleep deprivation reduces circulating androgens in healthy men. Arch Androl. (1983)
- González-Santos MR, et al. Sleep deprivation and adaptive hormonal responses of healthy men. Arch Androl. (1989)
- Cote KA, et al. Sleep deprivation lowers reactive aggression and testosterone in men. Biol Psychol. (2013)
- Leproult R, et al. Sleep loss results in an elevation of cortisol levels the next evening. Sleep. (1997)
- Backhaus J, Junghanns K, Hohagen F. Sleep disturbances are correlated with decreased morning awakening salivary cortisol. Psychoneuroendocrinology. (2004)
- Wu H, et al. Effects of sleep restriction periods on serum cortisol levels in healthy men. Brain Res Bull. (2008)
- Vgontzas AN, et al. Sleep deprivation effects on the activity of the hypothalamic-pituitary-adrenal and growth axes: potential clinical implications. Clin Endocrinol (Oxf). (1999)
- Caine-Bish N, et al. The effect of cold exposure on the hormonal and metabolic responses to sleep deprivation. Wilderness Environ Med. (2005)
- Opstad PK, et al. The thyroid function in young men during prolonged exercise and the effect of energy and sleep deprivation. Clin Endocrinol (Oxf). (1984)
- Sadamatsu M, et al. The 24-hour rhythms in plasma growth hormone, prolactin and thyroid stimulating hormone: effect of sleep deprivation. J Neuroendocrinol. (1995)
- Klingenberg L, et al. Sleep restriction is not associated with a positive energy balance in adolescent boys. Am J Clin Nutr. (2012)
- Koban M, Swinson KL. Chronic REM-sleep deprivation of rats elevates metabolic rate and increases UCP1 gene expression in brown adipose tissue. Am J Physiol Endocrinol Metab. (2005)
- Rechtschaffen A, Bergmann BM. Sleep deprivation in the rat: an update of the 1989 paper. Sleep. (2002)
- Takahashi Y, Kipnis DM, Daughaday WH. Growth hormone secretion during sleep. J Clin Invest. (1968)
- Sassin JF, et al. Human growth hormone release: relation to slow-wave sleep and sleep-walking cycles. Science. (1969)
- Gronfier C, et al. A quantitative evaluation of the relationships between growth hormone secretion and delta wave electroencephalographic activity during normal sleep and after enrichment in delta waves. Sleep. (1996)
- Van Cauter E, et al. A quantitative estimation of growth hormone secretion in normal man: reproducibility and relation to sleep and time of day. J Clin Endocrinol Metab. (1992)
- Obál F Jr, Krueger JM. The somatotropic axis and sleep. Rev Neurol (Paris). (2001)
- Saini J, et al. Continuous positive airway pressure treatment. Effects on growth hormone, insulin and glucose profiles in obstructive sleep apnea patients. Horm Metab Res. (1993)
- Brandenberger G, Weibel L. The 24-h growth hormone rhythm in men: sleep and circadian influences questioned. J Sleep Res. (2004)
- Ho KY, et al. Effects of sex and age on the 24-hour profile of growth hormone secretion in man: importance of endogenous estradiol concentrations. J Clin Endocrinol Metab. (1987)
- Brandenberger G, et al. Effect of sleep deprivation on overall 24 h growth-hormone secretion. Lancet. (2000)
- Spiegel K, et al. Adaptation of the 24-h growth hormone profile to a state of sleep debt. Am J Physiol Regul Integr Comp Physiol. (2000)