Effects of food consistency on sleep and wakefulness in rats

The present study examined the effects of food consistency, i.e., pelleted vs. powdered food, on the amount of REM and non-REM sleep, and wakefulness in rats fed with either type of food for 2 weeks. Polysomnography included neck muscle electromyogram (EMG), delta and spindle waves of the frontal electroencephalogram (EEG) and theta waves of the parietal EEG. We found that the amount of non-REM sleep during the dark period, when the rats were active, was significantly lower in rats fed the powdered food compared with those fed the pelleted food. This finding was most marked at the start of the dark period. Wakefulness was also longer in rats fed the powdered food during the dark period. The results indicate that food consistency affects non-REM sleep and wakefulness in rats, and that these effects may be related to changes in mastication.