Review on October 29, 2009
Night sweats have long been known to be a pesky symptom of menopause. The lowered levels of estrogen that trigger menopause are responsible for what causes night sweats. Without sufficient estrogen, the hypothalamus cannot properly regulate its medial preoptic region, which is responsible for the body's thermal regulation. The body's inability to control its own internal temperate is what causes night sweats. Night sweats are exactly like hot flashes, except that they occur during the night, making for some hot night sweats. It is known that disruptions to the body's internal temperature, whether they be from night sweats or some other cause, affect the quality of a woman's sleep. Some research has been done on the relationship between night sweats and sleep disruption, but this link is not yet fully understood.
Most of the studies on sleep in general have been done on women younger than thirty. The sleep of women old enough to go through any of the three stages of menopause (pre, peri and post-menopausal) has been studied much less, apart from its relationship to night flashes. However, we do know that women's reported quality and quantity of sleep declines with age. Furthermore, the incidence of hot flashes and night sweats is a predictor of poor sleep. The symptoms of disturbed sleep that night sweats help cause are: difficulty falling asleep, difficulty maintaining sleep, waking up too early or sleep that is chronically unsatisfying. The effect that night sweats have on sleep varies based on menopausal status: pre and perimenopausal women experience the most disruption in sleep due to night sweats. The relationship between night sweats and perimenopausal women was the most pronounced, although this might be due less to hormonal factors than the fact that these women have less experience in suffering from night sweats.
The 1994 study done by professors Woodward and Freedman, "The thermoregulatory effects of menopausal hot flashes on sleep," addresses the link between night sweats and poor sleep. The study monitored 12 post-menopausal women with night sweats for twenty-four hour periods, along with 7 post-menopausal women without night sweats to serve as a control group. The study's results show that night sweats are associated with an increase in stage 4 sleep. At this stage, the sleeper is in the deepest possible stage of physical rest. Women undergoing night sweats also experience one of the lightest stages of sleep, stage 2, for lesser periods of time than women who do not have night sweats. The study also found that the effects of these night sweats are the same whether they occur during sleep or 2 hours prior to the onset of sleep.