The effects of strenuous daytime physical exercise were examined in 12 healthy male volunteers. All-night electrophysiological recordings were made and blood was sampled during sleep by indwelling venous catheter.
Plasma growth hormone levels were significantly increased after exercise but the sleep electroencephalographic patterns of nights after exercise did not differ significantly from those of control nights. Plasma corticosteroids were decreased after exercise. It is suggested that higher levels of growth hormone are consistent with reparative processes during sleep.