We know that sleep deprivation causes us to reach for the unhealthy snacks, but new research has shown that a high-fat diet reduces the quality of the time we spend in our single or double beds. Researchers from the University of Minnesota found that prolonged exposure to a high-fat diet spoilt the quality of sleep experienced by rats. In an eight-week study, Professor Catherine M. Kotz of the University of Minnesota and Veterans Affairs Medical Center in Minneapolis led researchers as they examined rats 24 hours a day. They compared the sleep and wake states of rats after they had eaten a high-fat diet with those who consumed a standard laboratory diet. The findings showed that while the rats on the high-fat diet slept more, their sleep was fragmented. Furthermore, the extra sleep they had mostly took place during their usual wakeful hours. The Society for the Study of Ingestive Behavior (SSIB) compared this to excessive daytime sleepiness in obese humans. Professor Kotz said: "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 stabilising sleep and wake states. The current studies show that after high-fat diet-induced weight gain in rats, sleep quality is poor." She went on to explain that the study's findings suggest that poor sleep quality linked to a high-fat diet may be due to reduced orexin sensitivity.