Women who have severe hot flashes may have more chronic sleep problems than women who do not, according to a report in the June 26 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.

As many as 85 percent of menopausal women experience hot flashes, sensations of heat that may also involve sweating, according to background information in the article. Hot flashes often occur during the night and have been associated with insomnia, or difficulty sleeping. The symptoms of insomnia include problems falling asleep and/or staying asleep, sleep that is not restful and an overall dissatisfaction with sleep quantity or quality. Because many other factors also influence sleep in menopausal women, the exact link between hot flashes and insomnia has been difficult to establish.

Maurice M. Ohayon, M.D., D.Sc., Ph.D., Stanford University School of Medicine, Palo Alto, Calif., conducted telephone interviews with 3,243 individuals in California, including 982 women ages 35 to 65 years, between June 2003 and April 2004. Of the women, 562 (57.2 percent) were premenopausal; 219 (22.3 percent) were perimenopausal, meaning that they had irregular menstrual cycles with at least one period in the previous year; and 201 (20.5 percent) were postmenopausal, or had reported no menstrual bleeding in the previous year. Hot flashes were defined as mild if they usually did not involve sweating, moderate if they mostly involved sweating but did not require a woman to stop the activity she was pursuing and severe if they typically involved sweating and did require a woman to stop an activity.

About 33 percent of the women reported having hot flashes, including 12.5 percent of the premenopausal women, 79 percent of perimenopausal women and 39.3 percent of postmenopausal women. Of those who had hot flashes, about half reported that they were typically mild, while about one-third had moderate and about 15 percent had severe hot flashes. More than 81 percent of women with regular severe hot flashes had symptoms of chronic insomnia. These women reported difficulty falling asleep, non-restful sleep and overall dissatisfaction with their sleep patterns on a regular basis (at least three nights a week for at least the past six months). Women with mild hot flashes did not report these problems any more frequently than did women with no hot flashes. Women were also more likely to have problems staying asleep as their hot flashes became more severe.

The researchers also examined how insomnia related to women’s menopausal status and found that women in perimenopause were more likely to have difficulty falling asleep, non-restful sleep and overall dissatisfaction with sleep. One-third of perimenopausal and postmenopausal women reported that they believed insomnia was related to the development of menopause.

“This study provides evidence that severe hot flashes are associated with chronic insomnia in women aged 35 to 65 years,” the authors write. “The dramatic increase in insomnia in women with severe hot flashes indicates that severity of hot flashes should be routinely assessed in all studies of menopause.

“Treating hot flashes could improve sleep quality and minimize the deleterious consequences of chronic insomnia,” they conclude.

American Medical Association (AMA)