Sleep: Good for the Brain and the Belly

06/12/2010 05:12 am ET | Updated Nov 17, 2011

While it is widely known that adequate sleep is necessary for optimal mental performance, most do not know that adequate sleep can help prevent weight gain. Although people burn more calories when they're awake than when they are asleep (though your body still burns calories while sleeping!), those who are awake the most hours are often overweight. Read on to learn about this counter-intuitive phenomenon.

Nutrition Facts and Figures
Research shows that the number of hours slept influences an individual's risk of obesity. Many studies suggest that in both children and adults, the less they sleep, the heavier they are. At Columbia University, researchers found that people who slept six hours per night were 23 percent more likely to be obese than people who slept between seven and nine hours. Those who slept five hours were 50 percent more likely-while those who slept four hours or less were 73 percent more likely-to be obese.

Why is this so?
The fact that sleep deprivation is linked to obesity may have to do with what happens to your body when you deprive it of sleep. Two hormones are affected by sleep deprivation:

1) Leptin, which is released by fat cells, signals the brain to stop eating.

2) Ghrelin, which is made in the stomach and small intestine, signals the brain to keep eating.

These hormones influence how much one eats eat. Studies have shown that leptin levels are lower and ghrelin levels are higher in people who sleep fewer hours. Both of these hormone changes trigger you to eat more-therefore, the less you sleep the hungrier you are!

Another reason why those who are sleep deprived eat more may be due to the brain's response to leptin. When leptin levels decrease, the brain considers this a sign of starvation...and responds by slowing down one's metabolism and burning fewer calories. As a result, it becomes easier to put on weight since calories are burned at a slower rate.

In addition to having these hormonal changes signaling an individual to eat more, those who sleep less are also awake for more hours...hours during which they can eat more!

Obesity Can Also CAUSE Lack of Sleep
Another reason for the correlation between obesity and decreased sleep is a condition called obstructive sleep apnea, or sleep apnea. Sleep apnea is a condition where an individual's airway becomes obstructed, often by a large amount of fat tissue in the neck. The result is a cutoff in airflow, causing one to wake up numerous times throughout the night. Obesity is thus a major contributing factor for sleep apnea, and is often listed as one of its main causes. Sleep apnea is not a minor problem -- 10 years ago it was estimated that about 40 million Americans had sleep apnea and the number has likely increased greatly since2. Sleep apnea increases one's risk for developing high blood pressure, coronary heart disease, diabetes, suffering strokes, and for having accidents during the day.

LIVESTRONG Nutritionist, Alyse Levine, Offers Advice
The less we sleep the more at risk we are for obesity, and the more obese we get the more at risk we are for sleep disorders. Along with following a healthy, well-balanced diet and engaging in regular physical exercise, getting at least seven to eight hours of sleep per night is an important factor in maintaining a healthy weight.

Los Angeles nutritionist Alyse Levine MS, RD, founder of NutritionBite. Visit her profile on LIVESTRONG.COM.

Learn more about Diet & Nutrition at LIVESTRONG.COM and join over 9,360 members who Dare to Get More Sleep.

As Co-Founder of The Daily Plate on LIVESTRONG.COM, Joe Perez has made it his mission to empower people to eat smarter and to lead healthier lifestyles. "Curious Joe" works with editors, experts and contributors to feature health, fitness and diet articles and tools that empower its community.