Figure 1.

Sleep patterns after weight gain and weight loss in mice. The 24-h patterns of wakefulness, NREMS, and REMS are displayed in 6-h blocks. In the weight gain/loss group, the weight gain (after 6 weeks feeding with high-fat food) decreased wakefulness and increased NREMS and REMS (left). These alterations returned to the baseline (week 0) at week 10 (after 4 weeks of refeeding with regular food). The control animals did not show significant alterations in the amounts of wakefulness, NREMS, and REMS (middle). In the weight gain only group (right), the amount of wakefulness was significantly decreased and the amount of NREM sleep was significantly increased at week 6 and week 10 compared to baseline. The time is expressed as minute/6 hours. The error bars indicate the standard error. The horizontal thick black bars above the abscissa indicate the dark period.