Could losing weight or changing your diet help you sleep better?
A new study from the University of Pennsylvania suggests it could.
The relationship between obesity and sleep has been a hot topic lately. Obesity is a risk factor for poor sleep quality and daytime sleepiness whether or not people have sleep apnea. Studies have shown that sleep problems improved after patients had weight-loss surgery, even when they were still obese.
Isaac Perron, a doctoral student in neuroscience at Penn, was curious about whether weight, weight change or diet is more important when it comes to sleep disruption.
In the new study published in the journal Sleep, he tested how sleep was affected when 26 mice were fed regular chow or high-fat food. The group fed a high-fat diet for eight weeks gained 30 percent more weight than the mice on regular food. The fat mice slept an extra hour a day and had more fragmented sleep.
Mice typically are awake for 12.6 to 13.3 hours per day. They're nocturnal, so they're lively at night. They tend to take a "little siesta" during their waking period, Perron said. The extra sleeping the obese mice did was during what should have been their awake time.
The more surprising results came when the Penn team tried something else. They switched some of the fat mice back to regular chow and gave the leaner mice high-fat food. After a week, the mice in both groups weighed about the same amount. However, their sleep patterns were markedly different.
After only a week of dietary change, the mice on the high-fat diet were sleeping as badly as the obese mice had. The heavy mice eating leaner food were sleeping normally again.
This doesn't tell you whether the key factor was the high-fat diet or the fact that the heavy mice were losing weight. "The only conclusive thing we can say is that it's not the body weight," Perron said.
While this theory needs to be confirmed in humans, the potentially positive message, he said, is that obese people may not have to lose all their extra weight to improve their sleep.
He said that mice are generally considered a good model for studying human sleep.
Increasingly, scientists believe that diet or weight affect chemical signals to the brain that determine how and when we sleep. Exactly how that works is "still a pretty big black box," Perron said.
Figuring that out is the subject of the rest of his Ph.D. work.