Study Links Level of Daytime Sleepiness and Alertness with Diet

Many would be surprised to know that the type of food one eats is linked to the levels of sleepiness or alertness during the day.

According to a new study published in the journal Sleep, higher intake of fat was associated with increased objective daytime sleepiness, and increased intake of carbohydrates was related with increased alertness.

The study, "High fat intake is associated with physiological sleepiness in healthy non-obese adults", was independent of the subject's gender, age, BMI, total calorie intake and the total amount of sleep. The study found no correlation between the consumption of protein and sleepiness or alertness.

"Increased fat consumption has an acute adverse effect on alertness of otherwise healthy, non-obese adults," principal investigator Alexandros Vgontzas, MD, professor of psychiatry at the Penn State College of Medicine in Hershey, Pa, said in a press statement.  Vgontzas will present the study at the 27th annual meeting of the Associated Professional Sleep Societies LLC in Baltimore.

To prove their finding, the researchers conducted a study on 31 healthy non-obese normal sleepers who did not suffer from sleep apnea. They belonged to the age group of 18-65. They spent four consecutive nights in the sleep lab. On the fourth day, the researchers assessed the objective sleepiness with the help of the Multiple Sleep Latency Test (MSLT). They assessed their diet by providing food five times a day.

Prior to this, a study had shown how the diet composition affects subjective sleepiness. The new study adds to this by showing a strong co-relation between diet and objective sleepiness.

"Excessive daytime sleepiness and fatigue are very prevalent in the modern world and on the rise," said Vgontzas in a news release. "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."