Modafinil decreases food intake in humans subjected to simulated shift work

Abstract

In a limited number of studies modafinil has been shown to decrease food intake by laboratory animals and humans. The present study represents a secondary data analysis, in which the effects of modafinil on several measures of food intake were determined in humans living in a residential laboratory during simulated shift work. During this 23-day study, a wide selection of food items and beverages were freely available. During this double-blind, within-participant study, volunteers (N = 11) received oral modafinil dose (0, 200, or 400 mg) 1 h after waking for three consecutive days under two shift conditions: day shift and night shift. Shifts alternated three times during the study, and shift conditions were separated by an "off" day. Modafinil (200, 400 mg) dose-dependently decreased total caloric intake by approximately 18% and approximately 38%, respectively, regardless of shift condition, without selectively altering the proportion of total calories derived from carbohydrate, fat and protein. Ratings of "Hungry" were also significantly decreased by both active doses, but only immediately before the lunch break period. In addition, tolerance to the anorexic effects of modafinil was not apparent, as these effects remained stable across the three days of modafinil dosing. These findings show that modafinil produced clear reductions in food intake and suggest that future prospective studies should examine the drug in obese participants.

Figure 1

Upper Panels: Total kilocalories consumed as a function of modafinil dose (placebo, 200, 400-mg) and day within condition. Lower Panels: Number of eating occasions as a function of modafinil dose (placebo, 200, 400-mg) and day within condition. Left panels display results from the day shift and the right panels from the night shift. Error bars represent one SEM. An * indicates significantly different from placebo (p < 0.05). An § indicates significantly different from 200 mg (p < 0.05).

Figure 2

Grams of carbohydrate (upper panels) and fat (lower panels) intake as a function of modafinil dose (placebo, 200, 400-mg) and day within condition. Left panels display results from the day shift and the right panels from the night shift. Error bars represent one SEM. An * indicates significantly different from placebo (p < 0.05). An § indicates significantly different from 200 mg (p < 0.05).