Sex hormones, sleep, and core body temperature in older postmenopausal women.

STUDY OBJECTIVES: Assessment of relationships between polysomnographic sleep, sex hormones, and core body temperature in postmenopausal women.

DESIGN AND PARTICIPANTS: Ten women aged 57 to 71 years, at least 5 years past menopause.

SETTING: Laboratory of Human Chronobiology at Weill Cornell Medical College.

INTERVENTIONS: N/A.

MEASUREMENTS AND RESULTS: Lower estradiol (E2) and higher luteinizing hormone (LH) levels were significantly correlated with indices of poor sleep quality. Relationships between LH and polysomnographic variables were more robust than those for E2. Significant increases from basal LH levels (i.e., LH pulses) 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. In addition, higher body core temperature prior to and during sleep was significantly correlated with poorer sleep efficiency and higher LH levels.

CONCLUSIONS: Most investigations of relationships between sleep, sex hormones, and body temperature have focused on perimenopausal women, menopausal phenomena such as hot flashes, the role of declining estrogen, and treatment with exogenous estrogen. The current results suggest that altered levels of both sex steroids and gonadotropins may contribute to sleep disturbance in older women and confirm the results of previous studies indicating that higher body core temperature is associated with poorer sleep quality, even in women without vasomotor symptoms. The findings also raise the possibility of alternate treatment avenues for menopause- and age-related sleep disturbance that focus on altering LH levels.