Washington, Oct 1 : Postmenopausal women sleep longer than premenopausal counterparts, but are less satisfied with the quality of their nap, say a new study, which blames follicle stimulating hormone (FSH) for the effect.
The study showed that FSH change during menopause is linked with increased objective sleep duration but poor subjective sleep quality.
In the study, researchers created sleep profiles for365 participants and found that postmenopausal women had deeper sleep and longer total sleep time than premenopausal women.
A faster rate of change in FSH was linked with slow wave sleep and sleep duration, suggesting that as women transitioned more rapidly from an endocrine perspective, they slept longer. On the other hand, FSH change was associated with poorer self-reported sleep quality.
"We found that it was not the level of the FSH that was predictive of sleep, bout how quickly these menopause transition changes - FSH changes - occurred when hormones were measured over a seven-year period," said principal investigator MaryFran Sowers, PhD, professor of epidemiology at the University of Michigan.
The findings indicated that women who are nearing the end of the menopause cycle, as reflected by the decreasing ratio of estradiol to testosterone, have more sleep consolidation, or uninterrupted sleep, than women who are in the early stages of menopause.
Estradiol is a sex hormone that has a critical impact on reproductive and sexual functioning.
"Sleep characteristics and quality were not affected by the level of estradiol or its rate of change. We believe that this is because estradoil levels do not decline gradually in most women (as is frequently and erroneously believed), and most of the fall in estradiol levels occurs within a year or two of the final menstruation period," said Sowers.
Menopause is a four-to-10 year multifaceted process occurring in women at mid-life and is linked with numerous factors that might trigger or exacerbate sleep disturbances.
The results also show that women with higher testosterone (at levels that are still considered to be normal), or who are close to the completion of the transition process, have less sleep discontinuity, or waking after the onset of sleep.
The cross-sectional sleep substudy utilized information obtained from the Study of Women's Health Across the Nation (SWAN) along with data collected for a sleep-study profile from 365 Caucasian, African-American and Chinese women. Besides, data was also gathered through objective in-home polysomnography and subjective measures such as the Pittsburgh Sleep Quality Index.
The study included a comprehensive analysis of sleep (a single sleep study that lasted for three nights) nested within an ongoing longitudinal study and was conducted at four of the seven SWAN clinical sites during 2003-2005.
The sleep study for the sleep profile began within seven days of the beginning of the follicular phase of the menstrual cycle in premenopausal women who were still menstruating. Polysomnography was conducted in the homes of participants.
The study is published in the latest issue of the journal Sleep.