During early menopause, women are more likely to experience sleep disruptions that worsen at certain points of the menstrual cycle, results published in the Journal of Clinical Endocrinology & Metabolism suggest.
“We found that perimenopausal women experience more sleep disturbances prior to menstruation during the luteal phase than they did during the phase after menstruation,” study researcher Fiona C. Baker, PhD, of the Center for Health Sciences at SRI International in Menlo Park, California, and the University of Witwatersrand in Johannesburg, South Africa, said in a press release.
“Measures of electrical brain activity found that the hormone progesterone influences sleep, even at this late reproductive stage in perimenopausal women.”
Women experience irregular menstrual cycles during perimenopause, the earliest stage of the menopausal transition, that arise from fluctuating hormone levels. Those in their 40s often experience symptoms like hot flashes and sleep disturbances beginning 3 to 5 years before onset of menopause, according to information from the Hormone Health Network.
For this laboratory study, the researchers evaluated how menstrual cycle phase affected sleep in 20 midlife women using polysomnogram and EEG. Participants also completed a survey on their sleep quality during the month before lab testing and underwent a blood test to measure hormone levels. They were studied on one night each in the follicular and luteal menstrual phases.
Eleven participants were diagnosed with insomnia, as defined by the DSM-IV.
Data indicated that both women with and those without insomnia experienced more awakenings (P=.003) and arousals (P=.025) per hour of sleep and a lower percentage of slow-wave sleep (P=.024) when progesterone levels were elevated (at least 3 ng/mL) during the luteal vs. the follicular phase.
Women in both groups had greater sleep spindle density (P=.007), longer sleep spindles (P=.037) and increased 14 Hz to 17 Hz EEG activity during the luteal phase (P<.05). However, for the 15-Hz to 16-Hz bin, this was only significant in women without insomnia, according to study results.
Sleep duration was shorter (P=.012) and wakefulness after sleep onset was also increased (P=.031) in women with insomnia, while sleep efficiency was lower (P=.034) in women without insomnia, regardless of menstrual cycle phase.
“Menstrual cycle variation in hormones is one piece in the overall picture of sleep quality in midlife women,” Baker said. “This research can lead to a better understanding of the mechanisms behind sleep disturbances during the approach to menopause and can inform the development of better symptom management strategies.”