Can't get a good night's sleep? Don't be quick to blame it on menopause.
Middle-aged women often complain that they sleep poorly, and both women and their health care providers point to menopause as the cause. But University of Michigan researchers Jane Lukacs and Nancy Reame say it may be time to put that assumption to rest.
In an article in the just-released April issue of the Journal of Women's Health, Lukacs, an assistant research scientist at the U-M School of Nursing, under the direction of nursing professor Reame, tested the connection between the hormone estrogen and women's sleep quality. Her conclusion: "Estrogen has been blamed for a lot, but that doesn't seem to be what's at work here."
To separate aging effects from menopause, Lukacs and her collaborators studied a group of women aged 20-52, and compared them to age-matched women who had gone through menopause, some of whom were using estrogen therapy. For example, she examined a 47-year-old woman still having regular menstrual cycles and compared her data to a 47-year-old woman who had not had regular cycles for 12 months.
They found total sleep time, time spent awake during the night, and efficiency of sleep time all were worse for older women than younger women, regardless of whether the older women were still having menstrual cycles and regardless of whether they used estrogen therapy. While young women around age 24 slept about seven hours (416.9 minutes), all women in their 40s, regardless of their estrogen levels or menopause status, got only about six to six-and-a-half hours of sleep (354.9-377.8 minutes).
Further, although many women have taken hormone replacement drugs to try to help their sleep, Lukacs and Reame found that for women who were not having hot flashes, there was little difference in sleep between post-menopausal women who were or were not taking estrogen supplements.
"Our findings fail to support the popular view that estrogen plays an important role in sleep enhancement," the article states. "The use of an estrogen patch or gel for three months … did not improve any objective measure of sleep architecture."
The research team studied 51 women who participated in an overnight sleep challenge at U-M Hospitals. Women underwent a 24-hour blood sampling protocol to examine their hormone levels and wore electrodes for sleep monitoring from 11 p.m. to 7 a.m. Researchers studied sleep stages, REM sleep and sleep disruption.
The researchers noted that because this study involved an in-hospital, one-night sleep observation, further research examining women's natural sleep patterns in their own homes over multiple nights could give more insight into why women sleep poorly at midlife.
They added that in the future, researchers could build on their study and look for such variants as oxygen saturation to look for sleep apnea, leg muscle movement during sleep, and patterns associated with hot flashes, determined by monitoring skin temperature. Hormone replacement therapy might diminish muscle movement during sleep and calm hot flashes, Lukacs said, which could account for some of the beliefs about estrogen improving sleep.
Lead author Lukacs continues to research women's bone health, a topic she has studied for several years. In 2003, she presented at the Endocrine Society's annual meeting with findings on the difference between aging and menopause as they relate to women's bones, in which she used a similar age matching technique as that applied in her sleep research.
She is working on a bone research presentation for this summer's Endocrine Society meeting in New Orleans June 16-19, as well. http://www.endo-society.org/scimeetings/endo2004/index.cfm
Other co-authors on the article are Julie Chilimigras, Jason Cannon and Sharon Dormire. The work was supported by grants from the National Institutes of Health while Lukacs was a Pfizer post-doctoral fellow at U-M School of Nursing.
Lukacs' earlier work on menopause: http://www.umich.edu/news/Releases/2003/Jun03/r061903b.html
Nancy Reame's faculty profile: http://www.nursing.umich.edu/faculty/reame_nancy.html
Journal of Women's Health: http://dandini.ingentaselect.com/vl=1993566/cl=30/nw=1/rpsv/catchword/mal/15409996/
U-M School of Nursing: http://www.nursing.umich.edu/
Contact: Colleen Newvine
Phone: (734) 647-4411
E-mail: [email protected]