Getting less than forty winks has a profound negative effect on metabolic processes that determine not only how we seek out and utilize food, but also how adept our bodies are at burning or storing calories.
Over prolonged periods, lack of sleep causes significant hormonal disruption and metabolic dysregulation that contribute in a big way to the development of obesity and its associated imbalances.
Hormones by Moonlight
Without adequate sleep time (generally considered to be 7.5 hours per night), the levels of ghrelin and leptin—two messenger molecules known to have considerable importance in determining body composition—are unbalanced (Sinha MK, et al. J Clin Invest: ;97(5):1344-7).
Leptin, which is released from fat cells and is responsible for signaling satiety and stimulating fat burning, is normally increased during periods of restful sleep while ghrelin, which has the opposite effects, is decreased. This balance allows the body to utilize its energy reserves and lower caloric intake.
When sleep time is decreased, the opposite metabolic pattern occurs: leptin is reduced and ghrelin rises, resulting in lowered fat burning and increased hunger (frequently taking the form of late night snacking).
In a recent study of twins on a reduced calorie diet at the University of Washington, researchers found that twins who were limited to 5.5 hours of sleep per night showed 55% less fat loss than the twins who were allowed to sleep 8.5 hours, even as total body weight loss stayed the same for both testing periods (Watson NF, et al. Sleep. 2012; 35(5):597-603).
Sweet, Sweet Sleep:
Loss of sleep also affects glucose tolerance, potentially influencing the development of obesity-related diabetes and contributing to weight gain.
In people who slept for only 4 hours each night, glucose tolerance was reduced by 40% in comparison to subjects who had full nights of sleep (Spiegel K, et al. Lancet. 1999: 354(9188):1435-9). Insulin response to glucose was also decreased by 30%. Young, healthy subjects were found to reach pre-diabetic states similar to insulin-impaired adults within only a week of sleep deprivation.
The effects of sleep deprivation do not take weeks or months to show up (as was previously assumed would be the case). Significant changes can be noted within 1 or 2 days.
Detrimental effects are not limited to those mentioned above: Sleep loss has also been associated with decreased TSH levels (resulting in lowered metabolic rate), increased evening cortisol (associated with insulin resistance), and aberrations in the release of growth hormone, which affects body composition.
Given the central role that sleep plays in regulating metabolism and body composition, the treatment of metabolic disorders and weight gain may be well complimented by careful assessment of a patient’s relationship with Dr. Sandman.
Ciel Patenaude recently completed her Masters of Arts degree in Integrative Health at the California Institute of Integral Studies. Her focus is on developing wellness programs and health care that integrates modalities from around the world and throughout medical history, alongside that which is currently used within conventional medical care.