The Effect of Daytime Exercise load on Sleep Structure and the Secretion of Growth hormone, Testosterone, Cortisol, beta-endorphin during Sleep

Kim, J H; Hong, S B; Yi, J Y; Cho, K C

Abstract

OBJECTIVES
The purpose of this study is to investigate the effect of exercise load on sleep structure and stress hormone secretion during sleep.
METHODS
Five male physical education students were included in this study after giving their written, informed consents in the Research Institute for Sports Science at the University of Hanyang. All subjects have performed for at least 3 years in a regular aerobic exercises such as football, basketball, and running. The subjects were divided into three groups ; NOE (non-exercise), MDE (middle duration exercise), LDE (long duration excercise). MDE group maintained a total of 120 min exercise, and LDE group maintained a total of 300 min exercise by football, basketball or badminton. All subjects were acclimatized to the experimental sleep condition by spending one night under expermental conditions, including the placement of an intravenous catheter. During the subsequent night (24: 00-08 :00), somnopolygraphic sleep recordings were obtained, and blood for measuring growth hormone, cortisol, testosterone, and beta-endorphin was collected every 120 min throughout the night. Blood samples were obtained from prominent forearm veins of subjects. Then, the samples were immediately placed in ice and centrifuged within 10 min at 3000 rpm at 4 degrees C. Statistical analyses were performed using the SPSS/PC+. Data were analyzed by one-way ANOVA with repeated measures.
RESULTS
No significant differences among groups were observed in sleep latency, total sleep time, stage 2 sleep, and slow wave sleep. However, daytime exercise produced significant changes in stage 1 sleep, REM sleep, stage 2 sleep latency, REM sleep latency and sleep efficiency. Stage 1 sleep, stage 2 sleep latency, and REM sleep latency significantly increased in LDE compared to those of NOE and MDE groups. But the amount of REM sleep significantly decreased in LDE. Sleep efficiency of MDE was higher than those of NOE and LDE. The blood concentrations of growth hormone, testosterone, and cortisol during night sleep were significantly lower in LDE than in NOE. beta-endorphin concentrations in blood during night sleep were not different among groups.
CONCLUSION
The daytime exercise load was significantly related to sleep structure and stress hormone secretion during night sleep. Long duration exercise showed a harmful effect on sleep structure and hormone secretion However, middle duration exercise had a beneficial effect on sleep structure and hormone secretion during sleep.