Effects of light physical exercise on sleep in middle-aged rats

The effects of physical activity on sleep were evaluated in 12-month-old rats. The animals (n = 18) were induced to walk or run for 45 min in a rota-rod treadmill while control mates remained in their home cages. Immediately after the trial, they were left free to sleep for four hours, during which their electroencephalographic activity was recorded. Baseline electroencephalogram showed no differences among groups in sleep parameters and spike wave discharges during wakefulness in all rats. Sleep variables and spike wave discharges remained constant in the controls over times. On the contrary, Student's t-test for paired data indicated a decrease in spike wave discharges in both walking and running rats while paradoxical sleep rose parallel with slow wave sleep in walking animals but declined in running rats, in spite of an increment in slow wave sleep. The results seem to indicate that: i) light exercise improves sleep quality in middle aged rats, provided it is not stressful and ii) physical activity supplies important benefits to waking brain by reducing spike wave discharges.