Perimenopause: Hormone Fluctuations Tied to Disrupted Sleep

Susan London

June 16, 2015

Perimenopausal women may have increased sensitivity to the normal hormone fluctuations of the menstrual cycle when it comes to getting a good night's sleep, suggests a cohort study published online June 16 in the Journal of Clinical Endocrinology and Metabolism.

Researchers led by Massimiliano de Zambotti, PhD, a research scientist at the Center for Health Sciences, SRI International, Menlo Park, California, performed polysomnography (PSG) and electroencephalography (EEG) in 20 healthy women who were in the early menopausal transition but still ovulating. Each woman was studied on 1 night in the follicular phase and 1 night in the luteal phase of the menstrual cycle.

The women were 49.6 years old, on average. Eleven of them met formal diagnostic criteria for insomnia, which they reported began at the same time as the menopausal transition.

Study results showed that the women's progesterone levels were significantly higher in the luteal phase than in the follicular phase, whereas estradiol levels did not differ by phase or by group. Only three of the women experienced hot flashes during the sleep studies.

Relative to peers without insomnia, women with insomnia had a significantly shorter sleep duration (P = .012), more wakefulness after sleep onset (P = .031), and a lower sleep efficiency (P = .034), as well as poorer subjectively reported sleep quality (P < .001).

However, the women had significantly more awakenings (P = .003) and arousals (P = .025) per hour of sleep and a smaller percentage of slow-wave sleep (P = .024) during the luteal phase compared with the follicular phase, regardless of whether they had insomnia or not.

In addition, both groups had significantly greater spindle density (P = .007) and longer spindles (P = .037) in the luteal phase. They also had increased EEG activity in the 14- to 17-Hz range (P < .05) in the luteal phase, although the difference in activity specifically in the 15- to 16-Hz range was significant only in the women who did not have insomnia (P < .001).

"[W]e show that women with ovulatory cycles in the early menopausal transition have more awakenings and arousals in the luteal phase, whether or not they have an insomnia disorder," the investigators write.

"Possibly the vulnerability to arousal we detected in the luteal phase is a precursor to a change in arousal levels as women transition menopause and experience further hormone changes and the emergence of hot flashes."

The authors note that the findings generally contrast with those seen in studies of younger women. These studies have found that although younger women may have poorer subjectively reported sleep quality in the luteal phase, their objective PSG measures of sleep, such as wakefulness after sleep onset and sleep efficiency, remain constant across the menstrual cycle.

"Taken together, our findings suggest that sleep in midlife women may be more vulnerable to the physiological changes associated with the luteal phase, although studies in larger samples are needed to directly compare the influence of menstrual cycle phase on the PSG and sleep EEG in young and midlife women," the investigators conclude.

The authors have disclosed no relevant financial relationships.

J Clin Endocrinol Metabol. Published online June 16, 2015. Full text

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