Advancements in sleep research have led to the development of new standards of what is normal sleep and arousal and new diagnostic tests for the detection of sleep disorders. Millions of adults have frequent or chronic complaints about the quality and quantity of their sleep. Sleep complaints increase with increasing age and are more common in women than in men and in women over 45 than in younger women. Sedative-hypnotic drugs are taken more frequently by women than men, and the incidence of use increases with increasing age. Studies of sleep and sleep disturbances during the perimenopausal period suggest that difficulty falling asleep and frequent nocturnal awakenings result from hormonal changes, vasomotor symptoms, and possibly psychologic factors. Other causes for sleep complaints in menopausal and postmenopausal women are occult sleep disorders, especially periodic leg movements in sleep and sleep apnea syndrome. Sleeping pills are inappropriate for most patients with sleep complaints. If sleep difficulties persist after a trial of good sleep hygiene, further evaluation at a sleep disorders center is indicated.