Sleep Problems? Estrogen Might Not Help

April 29, 2004 -- Women's midlife sleep problems can't be blamed entirely on estrogen, a new study suggests. It's more grist for the mill, as researchers seek to understand this problem that plagues many women.

Research has shown that estrogen offers only modest relief to sleep-deprived women - suggesting that other age-related changes might be causing the problem, writes lead researcher Jane L. Lukacs, PhD, MSN, with the University of Michigan School of Nursing in Ann Arbor. Her study appears in the current issue of the Journal of Women's Health.

"Our study suggests that sleep problems may be related to other age-related effects -- not to menopauseper se, and not to estrogen," Lukacs tells WebMD. "Sleep problems could be caused by declines in other hormones, like melatonin, growth hormones, or other sex hormones."

Closer Look at Estrogen's Effects

Indeed, studies have also tended to "lump perimenopausal women together," says Lukacs. They have not looked adequately at hormonal fluctuations, estrogen therapy, hot flashes, obesity, and other factors that could affect sleep, she explains.

Even more importantly, the women's ages have varied greatly in these studies -- by as much as 30 years, she writes.

To better understand the effects of aging and estrogen on sleep, Lukacs enrolled women at various stages of their menstrual life:

• 14 women were in their 20s (all premenopausal),

• 37 women were in their 40s - nearly one-third were still menstruating; about one-third were postmenopausal and taking estrogen; and about one-third were postmenopausal but not taking estrogen.

• None was severely overweight, had hot flashes or night sweats, or reported any sleep disorders -- factors that could skew the study results.

No Slumber Party

The sleep study was no casual sleepover: Each woman spent the night in a hospital sleep laboratory, trying to get a decent night's sleep. Trying -- despite blood samples drawn all night long, and despite numerous electrodes attached to her body, including her chin, to monitor sleep cycles.

"That's definitely what we call a 'sleep challenge,'" says Lukacs. "But that kind of stressor helps us tease out differences among the women."

When morning came, each woman rated the quality of her sleep. None of the older women (in their 40s) reported having any hot flashes or night sweats, she says. All reported having disrupted sleep.

Surprisingly: Overall, the 40ish women had worse sleep problems than the younger women. Whether they were menopausal or not -- whether they took estrogen or not - their age was the common factor, Lukacs reports.

"We anticipated that women still having normal menstrual cycles would have similar sleep as the younger women," she tells WebMD. "We also figured women on hormone therapy would have better sleep, that it would quell hot flashes or night sweats."

But there was no such pattern: "All three groups of [over age 40] women slept worse, so clearly estrogen was not a factor in this study," says Lukacs.

"It's not that we don't need sleep," she explains. "This suggests that sleep problems may be an effect of aging, but not of menopause." Her study also suggests that older women have more problems adapting to a new sleep environment.