A new study suggests that your level of sleepiness or alertness during the day may be related to the type of food that you eat.

“Increased fat consumption has an acute adverse effect on alertness of otherwise healthy, non-obese adults,” said principal investigator Alexandros Vgontzas, MD, professor of psychiatry at the Penn State College of Medicine in Hershey, Pa.

The research abstract, published recently in an online supplement of the journal SLEEP, involved 31 healthy, non-obese normal sleepers without sleep apnea, ranging in age from 18-65 years, who spent four consecutive nights in a sleep lab.

Results show that higher fat consumption was associated with increased objective daytime sleepiness, while higher carbohydrate intake was associated with increased alertness.  There was no relationship between protein consumption and sleepiness or alertness. These findings were independent of the subjects’ gender, age, and body mass index as well as the total amount of sleep they were getting and their total caloric intake.

“Excessive daytime sleepiness and fatigue are very prevalent in the modern world and on the rise,” said Vgontzas. “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.”