Many sleep-deprived individuals drag themselves through the day, skipping physical activity and relying on sugary pick-me-ups. But these habits don't fight off sleepiness for long. And even worse? Over time, they can contribute to weight gain or, at the very least, sabotage your efforts to lose those last few pounds.
Lack of sleep changes your appetite.
"We have very substantial research that shows if you shorten or disturb sleep, you increase your appetite for high-calorie dense foods," says Charles Samuels, MD, medical director of the Centre for Sleep and Human Performance in Calgary, Alberta. "On a simplistic level, your appetite changes."
Two hormones in your body play an important role in controlling appetite and satiety. Ghrelin stimulates appetite, causing you to eat; leptin suppresses appetite—so you'll stop eating—and stimulates energy expenditure. In a properly functioning brain, the two hormones are released on and off to regulate normal feelings of hunger. But research has shown that sleep deprivation can alter ghrelin and leptin levels.
"When sleep is restricted to four hours a night, ghrelin levels go up and leptin levels go down," says National Sleep Foundation spokesperson William Orr, PhD, president and CEO of the Lynn Health Science Institute in Oklahoma City. "So you have a greater amount of appetite and a greater amount of intake."