Sleep, Obesity and Health

Some may think that people who sleep less have more time to exercise, thus reducing the risk of weight gain. However, inadequate sleep has been linked to an increased risk of being overweight or obese. There is compelling evidence that chronic lack of sleep alters hormones in the blood that control appetite and promote weight gain (Chaput & Tremblay 2012). Chronic poor sleep, or lack of sleep, triggers more signals to the brain to eat and reduces signals that enough food has been eaten (Markwald et al. 2013).

The culprit is the hormone cortisol, which appears in a higher than normal level when sleep is poor. High cortisol levels increase cravings for high-fat “comfort” foods. Additionally, sleep deprivation decreases levels of leptin, a satiety-promoting hormone, and increases levels of ghrelin, an appetite-promoting hormone (Markwald et al. 2013). Van Caute et al. found that lack of sleep plays a major role in hormone release, glucose regulation and cardiovascular function (2008). Evidence also indicates that poor sleep may be a risk factor for obesity and type 2 diabetes.

In addition, sleep reduction appears to be an important, yet modifiable, risk factor for metabolic syndrome. Markwald et al. (2013) found that insufficient sleep over 5 days increased total daily energy expenditure by 5%. However, energy intake—especially at night, after dinner—exceeded the level needed to maintain energy balance. Insufficient sleep led to an average weight gain of 1.8 pounds thanks to changes in hunger and in the satiety hormones ghrelin and leptin, which signaled the body to store energy.
These findings suggest that eating more during periods of insufficient sleep is a physiological adaptation intended to provide energy for sustaining additional wakefulness. Markwald and colleagues also found that energy intake, especially of fats and carbohydrates, decreased when study participants were no longer sleep deprived.

To view the full article from the November-December 2013 IDEA Fitness Journal click here.