Several studies have been conducted looking at the correlation (degree of association) between body fat and sleep. There appears to be an inverse correlation (less sleep nightly being associated with more body fat) that is further associated with more fat mass gain over a period of 5 years
Although correlation research is not conclusive, there appears to be a persistent relationship between less sleep time and greater fat mass. This association persists after controlling for the most predictable potential confounding agents and is likely related to sleep time per se (Sleep time being what is most easily measured in epidemiological research)
During intentional caloric restriction (fat loss diets), it appears that a reduction of sleep by 3 hours (8.5 to 5.5) is associated with an unfavorable nutrient partitioning effect, making more weight loss come from lean mass rather than fat mass relative to a rested control.
Sleep deprivation may adversely affect nutrient partitioning during weight loss
At least acutely, sleep deprivation appears to increase hunger and may be more significant when the sleep deprivation coexists with a reduced caloric intake. In otherwise healthy women, this has been quantified at around a 20% increase in voluntary energy intake (and a slight increase in body weight of 0.4kg over 4 days).
Sleep deprivation has been noted to increase circulating leptin (29%).
Sleep deprivation, over time, may lead to higher fat mass gains (possibly secondary to hunger, which is reliably increased) although even short term sleep deprivation appears to hinder fat loss attempts via reducing the percentage of weight loss that is fat mass
Restriction of sleep produces a neural sleep wave pattern that is sometimes observed in depression, and well-being appears to be related to sleep as well. A reduction in sleep reduces higher levels of cognition such as problem solving.
Impaired sleep is associated with impaired cognitive function
There is a correlation between abnormal sleep patterns and metabolic syndrome, with less sleep and more irregular or disturbed sleep being positively correlated with the occurrence of the comorbidities of metabolic syndrome (insulin resistance, hypertension, obesity). Extending from insulin resistance, an increased occurrence of diabetes is seen in persons with poor sleep patterns although there appears to be an increased risk for both shortened sleep (5-6 hours; RR of 1.28 and 95% CI of 1.03-1.60) and prolonged sleep (8-9 hours; RR of 1.48 and 95% CI of 1.13-1.96) which has been noted in other trials and meta-analyses.
Both shortened as well as excessive sleep are associated with insulin resistance and an increased risk of diabetes in survey research. Persons with a 7-8 hour sleep pattern seem to be at the lowest relative risk, with similar increases in both the 5-6 hour range and the 8-9 hour range
Acute sleep deprivation is able to impair insulin signalling in isolated adipocytes in otherwise healthy young adults which is present after three weeks of 90 minute deprivation or five days of more severe restriction (60% reduction in time). This insulin resistance is associated with less Akt phosphorylation induced by insulin (a reduction of 20% after 4 hours sleep deprivation for a few days) and has been quantified at around a 20+/-24% reduction in sensitivity (IVGTT) or 11+/-5.5% (euglycemic-hyperinsulinemic clamp) in otherwise healthy men.
Studies administering significantly reduced sleep time for a single day (4 hours of sleep) also confirm insulin resistance in otherwise healthy persons.
Interventions that reduce sleep time by as little as 2 hours daily can induce a state of insulin resistance in otherwise healthy persons within a week, and halving sleep time to 4 hours or less is able to induce insulin resistance after a single night
Sleep time appears to be an individual predicting factor for both total and free testosterone in the morning in older men, and during the process of aging the decline in testosterone (associated with aging) is further associated with perturbed sleep patterns. One study, however, has failed to find an associated with sleep time overall and serum testosterone.
A study assessing chronotype of subjects (relationship of body functions to the time of day, such as a 'morning' or 'evening' person) assessed via the Composite Scale of Morningness (CSM) noted that chronotype was associated with testosterone rather than total sleep time, with evening-orientated persons being associated with a higher testosterone level. It suggests that past studies finding a relationship between evening testosterone and sleep time (not deprivation studies, but associative studies) may be confounded with daily fluctuations of testosterone as chronotype is independent of sleep duration.
In general, sleep appears to be somewhat associated with testosterone levels. The strength of the correlation is not remarkable, but studies have at least noted some form of relationship. One study suggests that this may be more indicative of chronotype than overall sleep time, however, with those two factors being correlated but independent
One study (measuring testosterone for one day during waking hours) in young male subjects sleeping 8 hours routinely that cut sleep by 3 hours for a period of 5 days reduced testosterone by an average 10.4% relative to rested control, suggesting that acute sleep deprivation is able to influence testosterone levels. Another (similarly small) controlled study noted that despite weird fluctuations in FSH between persons, that sleep deprivation in young men noted a 30.4% decrease in testosterone that was accompanied by a decrease in DHT (26.4%) and Androstenedione (32.6%). One study using 60% sleep deprivation (10 hours routinely was then reduced to 4) for a period of 5 days noted a trend for reduced testosterone but failed to reach statistical significance despite an increase in SHBG.
This decrease in androgens occurs during 24 hours of sleep deprivation as well, but doesn't increase further beyond this time point.
One study has been conducted on outright sleep deprivation for one night (33 hours straight without sleep) has found an acute reduction in testosterone levels coupled with less reactive aggressiveness.
A single night without sleep is enough to decrease androgen production, and moderate daily sleep deprivation reliably reduces androgen levels (Testosterone levels being the most frequently measured) by some 10–30%.
Cortisol is a hormone that mediates the process of waking up, and shows a predictable circadian rhythm of being high in the morning while lower at night prior to sleep.
While some studies have admittedly found no significant effect or mild sleep deprivation over a few days on cortisol, numerous studies have noted increases seen with a single night or 5 days which can reach 51+/-8%.
The studies that find increases in cortisol tend to measure whole-day cortisol secretion, and may be showing an increase due to cortisol being increased in the evening following sleep deprivation. Morning readings of cortisol following sleep deprivation are actually reduced, and as such sleep deprivation appears to dysregulate and normalize the normally circadian rhythm of cortisol although overall exposure to cortisol goes upwards.
Cortisol normally follows a pulsative pattern and is higher in the morning and lower at night. Sleep deprivation dysregulates this, and causes a normalization of sorts of this pulsatile pattern (reducing morning cortisol, increasing serum cortisol) while whole-day exposure to cortisol goes up slightly
Sleep deprivation in otherwise healthy females has been noted to increase thyroid hormones T3 (19%) and T4 (10%) although other trials have failed to find an alteration in thyroid hormones with 33 hours acute sleep deprivation or chronic sleep deprivation. One study that measured thyroid stimulating hormone (TSH) noted that it was elevated during acute sleep deprivation but this has not been observed with chronic sleep deprivation.
Practical sleep deprivation either absolutely for one day or a reduction over a few days does not have consistent evidence for its effects on thyroid hormone levels
Diet induced thermogenesis may be slightly suppressed with sleep deprivation and cold-induced thermogenesis does not appear to be affected. At least in rats, sleep deprivation actually increases thermogenesis (resulting in weight loss despite increased food intake) in accordance with symptoms of sleep deprivation in rats (hyperphagia, weight loss, elevated energy expenditure, increased plasma catecholamines, hypothyroidism, reduction in core temperature, deterioration in physical appearance).
Studies that measure metabolic rate or total energy expenditure fail to find significant differences between normal sleep patterns and deprivation or possibly an overall increase in metabolic rate that is due to more spontaneous physical activity (ie. movement).
Metabolic rate is not reduced with sleep deprivation, and some evidence suggests that it is actually increased with sleep deprivation (either inherently as seen in rats, or secondary to an increase in physical activity)
A major pulse of growth hormone occurs shortly after falling asleep in relation to slow wave sleep and delta waves (0.5–3.5Hz), this spike accounts for approximately 50% of the daily AUC (Area-under-curve; a measure of overall exposure) of growth hormone in otherwise healthy young men. The association between the GH pulse and slow wave sleep is not seen at all times and some authors suspect that slow wave sleep is not an inducer of growth hormone but a coordinator of pulses (thus forcing a correlation).
Overall growth hormone secretion appears to be greater in youth and in women relative to older individuals and men, respectively; the increase seen in women is due to higher daytime levels being positively influenced by estrogen.
Sleep mediates the largest daily spike of growth hormone, which in young persons accounts for approximately half of daily exposure
Studies using sleep deprived persons that note a decline in growth hormone (due to lack of sleep and thus missing the pulse) note that daily GH production increases, but only enough to approximately compensate. This may be due to chronic sleep deprivation (6 nights of 4 hours sleep) causing a predictable biphasic GH pulse pattern or one study noting that night workers who had a small (16.8+/-3.3%) sleep pulse had sporadic pulses throughout the day to normalize the AUC.
It appears that when the pulse of GH seen with sleep is disrupted, that the body compensates during the day and overall daily exposure to GH is left not significantly different
For more information, see ten tips for better sleep.
- How eating better can make you happier
- I'm not too tired to stuff my face
- Can supplemental vitamin D improve sleep?
- Does ZMA cause weird dreams?
- Ten tips for better sleep
- How valid is BMI as a measure of health and obesity?
- Does ejaculation affect testosterone levels?
- Does creatine cause hair loss?
- Do herbal aphrodisiacs work?
- Does ashwagandha increase testosterone?
- What is 'roid rage'?
- Can creatine increase your testosterone levels?
- Is semen high in protein?
- How can you increase testosterone naturally?
- Four Testosterone Boosters and Sketchy Research
- Does Garcinia Cambogia help with weight loss?
- Can hypothyroidism lead to fat gain?
- How do I stay out of "starvation mode?"
- Measuring body fat percentage: It's an accuracy thing
- Does eating at night make it more likely to gain weight?
- Does diet soda inhibit fat loss?
- How to minimize fat gain when you binge
- A compound from beer may help fat loss
- Can one binge make you fat?
- Will carbs make me fat?
- How do I get a six-pack?
- How does protein affect weight loss?
- What should you eat for weight loss?
- Will lifting weights convert my fat into muscle?
- How do I lose fat around my belly?
- Does high-protein intake help when dieting?
- Does eating fat make you fat?
- Is diet soda bad for you?
- How to minimize fat gain during the holidays
- I have lost significant weight and now have loose skin. How can I tighten up my skin?
- Low-fat vs. low-carb? Major study concludes: it doesn’t matter for weight loss
- Does aspartame increase appetite?
- Is my “slow metabolism” stalling my weight loss?
- The lowdown on intermittent fasting
- Will eating breakfast keep you lean?
- Do you need to detox?
- Is it really that bad to skip breakfast?
- Will my breasts shrink with weight loss?
- 5 little-known facts about protein
- Whey vs soy protein: which is better when losing weight?
- Short sleep duration in association with CT-scanned abdominal fat areas: the Hitachi Health Study. Int J Obes (Lond). (2012) Yi S, 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) Park SE, et al.
- Sleep duration and five-year abdominal fat accumulation in a minority cohort: the IRAS family study. Sleep. (2010) Hairston KG, et al.
- Sleep duration and body mass index in twins: a gene-environment interaction. Sleep. (2012) Watson NF, et al.
- The association between short sleep and obesity after controlling for demographic, lifestyle, work and health related factors. Sleep Med. (2013) Di Milia L, Vandelanotte C, Duncan MJ.
- Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. (2010) Nedeltcheva AV, et al.
- Acute Sleep Deprivation Enhances the Brain's Response to Hedonic Food Stimuli: An fMRI Study. J Clin Endocrinol Metab. (2012) Benedict C, et al.
- Sleep restriction leads to increased activation of brain regions sensitive to food stimuli. Am J Clin Nutr. (2012) St-Onge MP, et al.
- Influence of partial sleep deprivation on energy balance and insulin sensitivity in healthy women. Obes Facts. (2008) Bosy-Westphal A, et al.
- Impact of sleep debt on physiological rhythms. Rev Neurol (Paris). (2003) Spiegel K, Leproult R, Van Cauter E.
- Optimism and Self-Esteem Are Related to Sleep. Results from a Large Community-Based Sample. Int J Behav Med. (2012) Lemola S, et al.
- Sleep on it, but only if it is difficult: Effects of sleep on problem solving. Mem Cognit. (2012) Sio UN, Monaghan P, Ormerod T.
- Sleep duration and cardiometabolic risk: a review of the epidemiologic evidence. Best Pract Res Clin Endocrinol Metab. (2010) Knutson KL.
- Association between short sleep duration and high incidence of metabolic syndrome in midlife women. Tohoku J Exp Med. (2011) Choi JK, et al.
- Association between sleep duration and metabolic syndrome in a population-based study: Isfahan Healthy Heart Program. J Res Med Sci. (2011) Najafian J, et al.
- Quantity and quality of sleep and incidence of type 2 diabetes: a systematic review and meta-analysis. Diabetes Care. (2010) Cappuccio FP, et al.
- Sleep duration as a risk factor for incident type 2 diabetes in a multiethnic cohort. Ann Epidemiol. (2009) Beihl DA, Liese AD, Haffner SM.
- 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) Chaput JP, et al.
- Sleep duration is a potential risk factor for newly diagnosed type 2 diabetes mellitus. Metabolism. (2011) Chao CY, et al.
- Impaired insulin signaling in human adipocytes after experimental sleep restriction: a randomized, crossover study. Ann Intern Med. (2012) Broussard JL, 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) Robertson MD, et al.
- Impact of Five Nights of Sleep Restriction on Glucose Metabolism, Leptin and Testosterone in Young Adult Men.
- Sleep restriction for 1 week reduces insulin sensitivity in healthy men. Diabetes. (2010) Buxton OM, et al.
- A single night of partial sleep deprivation induces insulin resistance in multiple metabolic pathways in healthy subjects. J Clin Endocrinol Metab. (2010) Donga E, et al.
- Association between sleep and morning testosterone levels in older men. Sleep. (2007) Penev PD.
- Middle-aged men secrete less testosterone at night than young healthy men. J Clin Endocrinol Metab. (2003) Luboshitzky R, Shen-Orr Z, Herer P.
- Chronotype but not sleep length is related to salivary testosterone in young adult men. Psychoneuroendocrinology. (2012) Randler C, et al.
- Validation of the full and reduced Composite Scale of Morningness.
- An actigraphic validation study of seven morningness-eveningness inventories.
- A marker for the end of adolescence. Curr Biol. (2004) Roenneberg T, et al.
- Effect of 1 week of sleep restriction on testosterone levels in young healthy men. JAMA. (2011) Leproult R, Van Cauter E.
- Sleep deprivation reduces circulating androgens in healthy men. Arch Androl. (1983) Cortés-Gallegos V, et al.
- Sleep deprivation and adaptive hormonal responses of healthy men. Arch Androl. (1989) González-Santos MR, et al.
- Sleep deprivation lowers reactive aggression and testosterone in men. Biol Psychol. (2013) Cote KA, et al.
- Sleep loss results in an elevation of cortisol levels the next evening. Sleep. (1997) Leproult R, et al.
- Sleep disturbances are correlated with decreased morning awakening salivary cortisol. Psychoneuroendocrinology. (2004) Backhaus J, Junghanns K, Hohagen F.
- Effects of sleep restriction periods on serum cortisol levels in healthy men. Brain Res Bull. (2008) Wu H, et al.
- Sleep deprivation effects on the activity of the hypothalamic-pituitary-adrenal and growth axes: potential clinical implications. Clin Endocrinol (Oxf). (1999) Vgontzas AN, et al.
- The effect of cold exposure on the hormonal and metabolic responses to sleep deprivation. Wilderness Environ Med. (2005) Caine-Bish N, et al.
- The thyroid function in young men during prolonged exercise and the effect of energy and sleep deprivation. Clin Endocrinol (Oxf). (1984) Opstad PK, et al.
- The 24-hour rhythms in plasma growth hormone, prolactin and thyroid stimulating hormone: effect of sleep deprivation. J Neuroendocrinol. (1995) Sadamatsu M, et al.
- Sleep restriction is not associated with a positive energy balance in adolescent boys. Am J Clin Nutr. (2012) Klingenberg L, et al.
- Chronic REM-sleep deprivation of rats elevates metabolic rate and increases UCP1 gene expression in brown adipose tissue. Am J Physiol Endocrinol Metab. (2005) Koban M, Swinson KL.
- Sleep deprivation in the rat: an update of the 1989 paper. Sleep. (2002) Rechtschaffen A, Bergmann BM.
- Growth hormone secretion during sleep. J Clin Invest. (1968) Takahashi Y, Kipnis DM, Daughaday WH.
- Human growth hormone release: relation to slow-wave sleep and sleep-walking cycles. Science. (1969) Sassin JF, 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) Gronfier C, 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) Van Cauter E, et al.
- The somatotropic axis and sleep. Rev Neurol (Paris). (2001) Obál F Jr, Krueger JM.
- Continuous positive airway pressure treatment. Effects on growth hormone, insulin and glucose profiles in obstructive sleep apnea patients. Horm Metab Res. (1993) Saini J, et al.
- The 24-h growth hormone rhythm in men: sleep and circadian influences questioned. J Sleep Res. (2004) Brandenberger G, Weibel L.
- 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) Ho KY, et al.
- Effect of sleep deprivation on overall 24 h growth-hormone secretion. Lancet. (2000) Brandenberger G, et al.
- Adaptation of the 24-h growth hormone profile to a state of sleep debt. Am J Physiol Regul Integr Comp Physiol. (2000) Spiegel K, et al.