We have previously reported that stretch training is effective in promoting improvement of sleep-related problems. However, the mechanisms underlying this effect remain unclear. This study aimed to investigate the effects of brief and low-intensity stretching exercises on physiological and psychological responses in relation to sleep and mental health. We examined changes in core temperature, stress, and mood states in response to acute exercise. 　Eight women （mean age, 49.4 ± 5.8 years） who were not taking any medications affecting sleep volunteered to participate in this study. The exercise program required 10 min of stretching using yoga techniques and poses. Exercise and control programs were randomly performed in a cross-over trial in each subject. Each trial was started at 1:00 pm; stretching began at approximately 2:00 pm. Rectal temperature, salivary cortisol levels, and mood states（ pleasantness, relaxation, anxiety） were measured before and after stretching. 　Significant interactions in two factors（ trial and time progress） were identified for rectal temperature, cortisol levels, and pleasantness score. A greater degree of change in rectal temperature was seen with the exercise program than with the control program. Cortisol levels increased slightly in the control program and decreased in the exercise program. Pleasantness scores increased over time in both programs, but the degree of change was greater in the exercise program than in the control program. 　Peripheral heat dissipation at bedtime after a rise in core temperature of less than 0.5℃ has been reported to facilitate sleep onset. The present study found that a suitable rise in core temperature was achieved after stretching. Stress response and pleasantness also improved with stretching. These changes after exercise seem to contribute to improved emotional condition. 　In conclusion, performance of brief and low-intensity stretching exercises may promote improvement of sleep-related problems by causing a suitable rise in core temperature, and may contribute to mental health by reducing stress and improving mood status in middle-aged women.

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