Excessive training is reported to cause sleep disturbances and mood changes. We examined sleep and psychological changes in female swimmers across a competitive swimming season, that is, at the start of the season (onset), during peak training period (peak), and after a precompetition reduction in training (taper). For each phase, polysomnographic recordings, body composition, psychological parameters, and swimming performance were obtained. A daily training log and sleep diary were maintained for the entire study period. Sleep onset latency (SOL), time awake after sleep onset, total sleep time (TST), and rapid eye movement (REM) sleep times were similar at all three training levels. Slow wave sleep (SWS) formed a very high percentage of total sleep in the onset (26%) and peak (31%) training periods, but was significantly reduced following precompetition taper (16%), supporting the theory that the need for restorative SWS is reduced with reduced physical demand. The number of movements during sleep was significantly higher at the higher training volumes, suggesting some sleep disruption. In contrast to other studies, mood deteriorated with a reduction in training volume and/or impending competition.
Edblo Sleep Laboratory & Applied Physiology Laboratory, Department of Physiology, University of the Witwatersrand Medical School, Johannesburg, SOUTH AFRICA
Submitted for publication April 1995.
Accepted for publication August 1996.
We thank Edblo (Africa) Limited and the University of the Witwatersrand Medical Faculty Research Endowment Fund and Research Committee for financial support, as well as the swimmers who participated in the study.
Address for correspondence: Prof. G. Rogers, Department of Physiology, University of the Witwatersrand, 7 York Road, Parktown 2193, South Africa. E-mail: firstname.lastname@example.org.