A lack of sleep can cause or contribute to a number of health problems. Sleep isn’t just rest, it is a profound opportunity for healing. Sleep deprivation can also undermine one’s ability to lose weight. When either quality or quantity of sleep becomes compromised, a hormonal imbalance ensues which affects your body’s metabolism.
Previously, we have discussed the balancing act between your fat storage hormone insulin and your stress balancing hormone cortisol. A prolonged or repeated elevation in one or both of these hormones can underly weight gain. This is why a high-stress lifestyle and high-carbohydrate processed foods are a double whammy to your metabolism. Compound this with a lack of sleep, and metabolic derangement is all but assured.
A shortened night or lack of deep sleep (such as the non-restorative sleep characteristic of sleep apnea), causes an imbalance in two additional metabolism regulating hormones; ghrelin and leptin. Ghrelin is an appetite stimulating hormone and leptin is the hormonal signal for satiation. Between the two, they provide the biofeedback between stomach and nervous system to regulate our need for food and our sense of being full and satisfied.
For reasons which are not yet clear, less than seven hours of sleep has been experimentally shown to raise ghrelin and lower leptin. This translates as an increase of appetite and a decrease in the sense of fullness from what you have eaten – not a very good combination for someone trying to lose weight. Even more unfortunate is the increased cravings for high-carbohydrate foods in the group studied.
The time in which you eat has also been observed to directly influence weight gain. In one study, two cohorts of mice were fed the same amount of calories, yet the group fed at night gained more weight than the mice fed only during the day. Additional research suggests an interplay between our circadian rhythm and the modulation of these hormones. Thus, if we are awake longer into the evening, not only are we likely to eat more, but the food we do eat both night and day is more likely to cause weight gain.
This explains, in part, the observation of weight loss in a patient diagnosed with sleep apnea who has been using a CPAP machine. Deep restful sleep will naturally lead to a balance in both leptin and ghrelin, but also cortisol. The act of apnea is a significant stress on the body, and stress is followed by a release of cortisol. Cortisol raises your blood sugar to help your body cope with and prepare for future stress. From your metabolism’s perspective, the blood sugar elevation derived from a cortisol spike could just as well have been a piece of chocolate cake. Without the stress of sleep apnea, the body now skips this figurative nighttime dessert.
Because of the myriad of factors, being an insomniac does not necessarily lead to obesity. However, if you are overweight and don’t get close to eight hours of deep restorative sleep per night, your weight loss efforts will be significantly compromised. Is it any wonder why we call it beauty sleep?
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