Altered levels of both sex hormones and gonadotropins may contribute to sleep disturbance in older postmenopausal women, according to a study published in the December 1 issue of the journal SLEEP.
The study, authored by Patricia J. Murphy, PhD, of Weill Cornell Medical School, looked at 10 women between 57 and 71 years of age, at least five years past menopause, examining possible links between objective sleep measures, nocturnal sex hormone levels, and night time body temperatures.
Hormone Levels, Sleeplessness and Menopause
In fertile women, an sharp rise in levels of luteinizing hormone, the LH surge, is what triggers ovulation.(1) Estradiol is the major estrogen hormone, and development of secondary sex characteristics in women is driven by it.(2)
Researchers found that lower estradiol and higher luteinizing hormone (LH) levels correlated meaningfully with indices of poor sleep quality, as in insomnia. Relationships between LH and quality of sleep were stronger than for estradiol.
Additionally, significant increases from basal LH levels occurred more frequently after sleep onset than prior to sleep onset, and 30 of 32 of these LH pulses occurred prior to long awakenings from sleep. Further, higher body temperature prior to and during sleep was significantly correlated with poorer sleep efficiency and higher LH levels.
“Few studies have measured gonadal hormones in women who are more than a couple of years postmenopause, and almost no studies have investigated, beyond menopause, whether endogenous levels of these hormones influence sleep,” said Dr. Murphy.
“Yet, perimenopausal and postmenopausal women share many of the same features of sleep disturbance, such as awakening in the early morning hours and an inability to return to sleep. Furthermore, several studies have shown that hot flashes and other vasomotor symptoms that influence sleep continue years beyond menopause in up to 40 percent of postmenopausal women.
Thus, the sleep difficulties that emerge at menopause often do not abate and may become compounded by age-associated disruption of circadian and homeostatic processes that regulate sleep.”
How does the hormone melatonin fit in these sleep problems? Melatonin levels in the blood vary in a cyclical pattern. Higher levels make a “signal” that forms part of the system regulating circadian sleep and wake cycles. Chemically, melatonin works by causing drowsiness to fall upon the mind.
Another recent study(3) looked at the timing of melatonin cycles in depressed and non-depressed postmenopausal women in order to gain a clearer understanding of the complex hormonal pattern in these women. The researchers, from the University of California, San Diego, found that the number of years a woman was past menopause predicted plasma melatonin peak level durations.
They also found that melatonin duration, body mass index, years past menopause, Follicle Stimulating Hormone level and sleep end time were correlated and significant predictors of depression scores. So are melatonin levels controlled by estrogen and gonadotropin levels? Further research is needed, but it seems that melatonin supplementation (4) at some point in the future could be on the list of sleep aids for postmenopausal women suffering from poor sleep.
3. Parry BL, Meliska CJ, Sorenson DL, LÃƒÂ³pez AM, MartÃƒÂnez LF, Nowakowski S, Hauger RL, Elliott JA. Increased Melatonin and Delayed Offset in Menopausal Depression: Role of Years Past Menopause, FSH, Sleep End Time and Body Mass Index. J Clin Endocrinol Metab. 2007 Nov 27 PMID: 18042653
4. Zhdanova I, Wurtman R, Regan M, Taylor J, Shi J, Leclair O (2001). “Melatonin treatment for age-related insomnia.”. J Clin Endocrinol Metab 86 (10): 4727 30. PMID 11600532.
Composite computer artwork by Neil Leslie, Wellcome Images Creative Commons.