Sleep Restriction Increases Hunger
What if I told you there was a pill that could improve your memory and productivity? The same medicine has been shown to increase muscle mass and decrease body fat. It has even been shown to improve mood and reduce anxiety. Would you be interested in this supplement? Well, guess what? It is free! We can take the supplement every single night, but most of us don’t. The supplement I am referring to is sleep.
Losing weight and getting in shape is very challenging for the everyday person, especially in America, where work comes first, and sleep comes second. We are encouraged to burn the midnight oil and told that that sleep is for the weak. Unfortunately, this couldn’t be further from the truth. According to Matthew Walker, a sleep neuroscientist, and author of Why We Sleep,
“the shorter your sleep, the shorter your life. The leading causes of disease and death in developed nations—diseases that are crippling health-care systems, such as heart disease, obesity, dementia, diabetes, and cancer—all have recognized causal links to a lack of sleep.”
The National Sleep Foundation recommends we sleep 7-9 hours a night. However, according to the CDC, 1 in 3 adults don’t get the recommended amount. For the last 50 years, sleep has been on a steady decline, and obesity has been on a steady climb. Research has shown a direct link between obesity and sleep deprivation, but why?
Sleep Deprivation Increases Weight
To figure out the link between sleep restriction and obesity, Andrea Spaeth and colleagues performed the following study: Effects of Experimental Sleep Restriction on Weight Gain, Caloric Intake, and Meal Timing in Healthy Adults. The study included 225 healthy adults, with 198 of them participating in the sleep restriction group and 27 of them in the control group (normal sleep). The sleep-restricted group slept four hours per night for five nights, while the control group slept 10 hours each night. In addition to the sleep restriction, the subjects in both groups were not allowed to exercise, but they did have access to books, television, and video games. Also, the participants were encouraged to eat as little or as much as they wanted throughout the day. By the end of the study, the sleep-restricted group had gained significantly more weight compared to the control group (1). (see graph below)
As you can see from the graph, the sleep restricted group gained 2.2 lbs versus the control group. Now, this may not seem significant, but the weight gain occurred in only five days. What if the study was extended for a month, or even a year?
Sleep Restriction Increases Hunger Hormones
The authors of the study believe that the delayed bedtime led to a higher calorie intake through increased meal frequency, but not through increased portion size. The scientists aren't sure exactly why the meal frequency increased, but they hypothesized that it could be due to the hunger hormone ghrelin. Sleeping less than four hours a night has been shown to increase ghrelin levels and augment hunger(2).
"Spiegel and colleagues found that subjects undergoing 2 nights of sleep restriction (4 h time in bed /night) with controlled energy intake...increased levels of ghrelin and decreased levels of leptin. These neuroendocrine changes were accompanied by significant increases in self-reported ratings of hunger and appetite, specifically for foods with high carbohydrate content (2)."
However, another sleep restriction study found no increases in ghrelin when subjects had unlimited access to food, especially in women(3). So I am not entirely sure if ghrelin is the reason for the meal frequency increase. Rather, it could just be due to a longer feeding window or boredom. Anecdotally, I eat the most when I am bored or up late. Nevertheless, regardless of the mechanism, the study shows that sleep deprivation increases the risk for weight gain and obesity. So, turn off the Netflix, and get some rest.
*For more information on sleeping better, head here