"Excessive daytime sleepiness and fatigue are very prevalent in the modern world and on the rise," study researcher Dr. Alexandros Vgontzas, M.D., a professor of psychiatry at Penn State College of Medicine, said in a statement. "It appears that a diet high in fat decreases alertness acutely, and this may have an impact on an individual’s ability to function and also public safety."
The study included 31 non-obese, healthy people between the ages of 18 and 65. None of the people had sleep apnea.
Researchers had the study participants spend four nights in a row in a sleep lab; the participants also had their daytime sleepiness and dietary habits recorded.
They identified the link between daytime sleepiness and increased fat consumption, as well as the link between alertness and increased carbohydrate consumption, even after accounting for factors like age, BMI, caloric intake and sleep duration. However, researchers did not find links between alertness or sleepiness and protein consumption.