Nearly 185 million adults and 24 million children in the United States are overweight or obese. In Philadelphia, an estimated 68 percent of adults are overweight or obese. Beyond impaired cognitive function, poor sleep is associated with a host of chronic health problems including depression, obesity, and hypertension. Additionally, the Centers for Disease Control and Prevention estimates that 50 to 70 million U.S. adults experience sleep or wakefulness disorders.
Weight loss due to dietary changes can improve sleepiness at any weight, says a study published in the journal Sleep, which the authors say reaffirms how weight fluctuations impact numerous aspects of sleep independent of body weight.
Previous studies have linked obesity with persistent sleepiness, lack of energy during the day, and poor sleep quality, all of which can be successfully combated with weight loss treatment. But until now, researchers have known little about the link between excessive weight, poor dietary habits, and sleep/wake abnormalities.
In the current research, obesity was studied using diet-induced obese mice. Half the mice were randomly chosen to receive regular chow (RC) while the other mice were fed a high-fat diet (HFD, more than three times higher in fat content) for eight weeks. At the end of that period, some of the mice were switched to the alternative diet for one week, causing newly-fed HFD mice to gain weight and newly-fed RC mice to lose weight, while the rest of the mice continued to consume their current diet.
After the ninth week, mice maintained on HFD weighed 30 percent more, slept more than one hour longer per day, and suffered from increased wake fragmentation (frequently slipping into sleep) compared to mice maintained on RC. The "diet switch" groups, however, had similar body weight at week nine, but completely different sleep/wake profiles when compared to each other.
"Our findings suggest body weight is a less important factor than changes in weight for regulating sleepiness," said the study's lead author, Isaac Perron, a PhD student in Neuroscience at the University of Pennsylvania. "Diet-induced obese mice that ate a regular chow diet for only one week showed the same sleep/wake profile as mice that ate a regular chow diet for nine weeks."