Twenty-one healthy men between 18 and 30 years of age were studied to determine the effects of midday food intake on sleep. Twelve subjects were administered liquid carbohydrate meals at lunchtime on 2 consecutive days. Subjects slept on 22 of the 24 study days for an average of 93 minutes during 3 hours of postprandial polysomnographic recording. Nine subjects were used as controls and were deprived of a lunch meal. Six of the nine subjects slept for an average of 30 minutes during the postprandial period. This time was significantly shorter than that of subjects in the meal condition (p < 0.005). There was no difference in latency to sleep onset following food intake between the two study groups. The results of this study suggest that lunchtime food intake does not promote the initiation of sleep, but that it does increase the duration of sleep episodes occurring during the postprandial period.