Weight gain induced by high-fat diet increases active-period sleep and sleep fragmentation

Using radio-telemetry, the authors measured 24-hour sleep and wake states after rats consumed a high fat diet for 8 weeks. Compared to rats that consumed a standard laboratory chow, the rats on the high-fat diet slept more but sleep was fragmented. The increased sleep time of the rats on the high-fat diet occurred mainly during the normally active phase of the day, resembling excessive daytime sleepiness observed in obese humans.

According to lead author, Catherine Kotz, "Studies in humans indicate a relationship between sleep quality and obesity. Our previous work in animals shows a link between good quality sleep, resistance to weight gain and increased sensitivity to orexin, a brain chemical important in stabilizing sleep and wake states. The current studies show that after high-fat diet-induced weight gain in rats, sleep quality is poor and orexin sensitivity is decreased. These findings suggest that poor sleep associated with weight gain due to a high-fat diet may be a consequence of reduced orexin sensitivity."

These studies highlight the impact of weight gain on sleep quality and a potential brain mechanism underlying these diet and weight-gain induced changes in sleep behavior.