Polysomnographic recordings were obtained in 10 subjects (5 men and 5 women) for three conditions: following masturbation with orgasm, following masturbation without orgasm, and after reading neutral material. The analysis of several sleep parameters did not reveal any effect of masturbation on sleep. These results suggest that physiological changes that occur during masturbation, with or without orgasm, have no major effect on sleep organization. Other factors associated with sexual activity and potentially responsible for sleepiness after orgasm are discussed, and further strategies to study the interrelationship of sexual activity and sleep are proposed.