Increased slow wave sleep and reduced stage 2 sleep in children depending on exercise intensity

Background: There is controversy about the consequences of physical exercise on human sleeping behaviors. Evidence suggests that voluntary physical exercise affects brain structures and functions. However, there are inconsistent data regarding the effects of exercise on sleep architecture and sleep continuity, especially the amounts of slow wave sleep (SWS) and rapid eye movement (REM) sleep. Objective: The aim of the present study was to investigate the effects of moderate and high intense physical exercise on vigilance state and sleep patterns in school-aged children. Methods: Eleven healthy children (12.6 +/- 0.8 years old) were recruited for this polysomnographic study and underwent two exercise sessions. The two exercise sessions on a bicycle ergometer were performed 3-4 h prior to bedtime, lasted 30 min and varied in intensity. The moderate-intensity exercise was at 65-70% of maximal heart rate (HRmax) while the high-intensity exercise was at 85-90% HRmax to exhaustion. Polysomnographic and physiological measurements, including oximetry, were made on three nights in random order and separated by I week. Vigilance tests were carried out before and after the three sleep periods. Results: Only high-intensity exercise resulted in a significantly elevated SWS proportion and less sleep in stage 2 as well as a higher sleep efficiency and shorter sleep onset latency. No significant effects on REM sleep were found. Conclusion: The results suggest that exercise intensity is responsible for the effects on stage 2 sleep and SWS in children and support the hypothesis of homeostatic sleep regulation. (C) 2007 Elsevier B.V. All rights reserved.