The effect of hormone therapy on serum melatonin concentrations in premenopausal and postmenopausal women: a randomized, double-blind, placebo-controlled study

The circadian variation of sleep and alertness of postmenopausal women

STUDY OBJECTIVES

Several factors may contribute to the high prevalence of sleep disturbances occurring in postmenopausal women. However, the contribution of the circadian timing system to their sleep disturbances remains unclear. In the present study, we aim to understand the impact of circadian factors on changes of sleep and alertness occurring after menopause.

METHODS

Eight healthy postmenopausal women and 12 healthy young women in their mid-follicular phase participated in an ultradian sleep-wake cycle procedure (USW). This protocol consisted of alternating 60-min wake periods and nap opportunities for ≥ 48 h in controlled laboratory conditions. Core body temperature (CBT), salivary melatonin, self-reported alertness, and polysomnographically recorded sleep were measured across this procedure.

RESULTS

In both groups, all measures displayed a circadian variation throughout the USW procedure. Compared to young women, postmenopausal women presented lower CBT values, more stage N1 and N2 sleep, and number of arousals. They also showed a reduced amplitude of the circadian variation of melatonin, total sleep time (TST), sleep onset latency (SOL), stage N3 sleep, and alertness levels. Postmenopausal women fell asleep faster and slept more during the biological day and presented higher alertness levels during the biological night than young women.

CONCLUSION

These results support the hypothesis of a weakened circadian signal promoting sleep and wakefulness in older women. Aging processes including hormonal changes may be main contributors to the increased sleep-wake disturbances after menopause.

Association of hormone therapy and changes of objective sleep quality in women of late menopausal transition with sleep disorder: a preliminary study

OBJECTIVE

The aim of this study was to investigate changes in objective sleep quality with hormone therapy (HT) in women with late menopausal transition.

METHODS

Healthy midlife women with sleep difficulty who received HT were included. Those undergoing late menopausal transition were screened. Sleep patterns and self-reported questionnaires were collected before and 10 weeks after starting HT.

RESULTS

Ten women who met the criteria (age, 50.1 ± 2.8 years) showed higher sleep efficiency and shorter wakefulness after sleep onset (WASO) 10 weeks after starting HT. However, no significant change was found in objective sleep quality after adjustment for multiple comparisons: sleep efficiency, 84.2 ± 7.7 versus 88.2% ± 4.7%, P = 0.037, adjusted P = 0.259; WASO, 59.0 ± 27.2 minutes versus 41.4 ± 17.4 minutes, P = 0.020, adjusted P = 0.140; average duration per awakening, 2.9 ± 1.0 minutes versus 2.2 ± 0.5 minutes, P = 0.033, adjusted P = 0.231. A better score of subjective sleep quality in the Pittsburgh Sleep Quality Index was observed 10 weeks after starting HT (2.0 ± 0.0 vs 1.2 ± 0.4, P = 0.006, adjusted P = 0.042), but sensitivity analysis did not show consistent results after adjustment for multiple comparisons (2.0 ± 0.0 vs 1.1 ± 0.4, P = 0.020, adjusted P = 0.140). Total scores of the Insomnia Severity Index and Menopause Rating Scale were better 10 weeks after starting HT (Insomnia Severity Index, 14.7 ± 3.0 vs 9.1 ± 3.8, P = 0.010; Menopause Rating Scale, 29.0 ± 5.2 vs 21.6 ± 3.0, P = 0.009) with consistent results in sensitivity analyses. There was no difference in the Epworth Sleepiness Scale before and after HT (7.2 ± 1.7 vs 8.6 ± 4.5, P = 0.309). The change in each objective sleep quality variable before and after HT showed strong positive or negative correlations with the change in only a few items in subjective sleep quality.

CONCLUSION

Women in the late menopausal transition period showed higher sleep efficiency and shorter WASO after HT; however, multiple comparisons showed no statistically significant difference in objective sleep quality between before and after HT.

Measuring serum melatonin in postmenopausal women: Implications for epidemiologic studies and breast cancer studies

BACKGROUND

Circulating melatonin is a good candidate biomarker for studies of circadian rhythms and circadian disruption. However, epidemiologic studies on circulating melatonin are limited because melatonin is secreted at night, yet most epidemiologic studies collect blood during the day when melatonin levels are very low, and assays are lacking that are ultrasensitive to detect low levels of melatonin reliably.

OBJECTIVE

To assess the performance of a refined radioimmunoassay in measuring morning melatonin among women.

METHODS

We used morning serum samples from 47 postmenopausal women ages 48-80 years without a history of breast cancer who participated in the San Francisco Bay Area Breast Cancer Study, including 19 women who had duplicate measurements. The coefficient of variation (CV) and intraclass coefficient (ICC) were estimated using the random effect model.

RESULTS

Reproducibility for the assay was satisfactory, with a CV of 11.2% and an ICC of 98.9%; correlation between the replicate samples was also high (R = 0.96). In the 47 women, serum melatonin levels ranged from 0.6 to 62.6 pg/ml, with a median of 7.0 pg/ml.

CONCLUSION

Our results suggest that it is possible to reliably measure melatonin in postmenopausal women in morning serum samples in large epidemiologic studies to evaluate the role of melatonin in cancer etiology or prognosis.

Effects of smartphone use with and without blue light at night in healthy adults: A randomized, double-blind, cross-over, placebo-controlled comparison

Smartphones deliver light to users through Light Emitting Diode (LED) displays. Blue light is the most potent wavelength for sleep and mood. This study investigated the immediate effects of smartphone blue light LED on humans at night. We investigated changes in serum melatonin levels, cortisol levels, body temperature, and psychiatric measures with a randomized, double-blind, cross-over, placebo-controlled design of two 3-day admissions. Each subject played smartphone games with either conventional LED or suppressed blue light from 7:30 to 10:00PM (150 min). Then, they were readmitted and conducted the same procedure with the other type of smartphone. Serum melatonin levels were measured in 60-min intervals before, during and after use of the smartphones. Serum cortisol levels and body temperature were monitored every 120 min. The Profile of Mood States (POMS), Epworth Sleepiness Scale (ESS), Fatigue Severity Scale (FSS), and auditory and visual Continuous Performance Tests (CPTs) were administered. Among the 22 participants who were each admitted twice, use of blue light smartphones was associated with significantly decreased sleepiness (Cohen's d = 0.49, Z = 43.50, p = 0.04) and confusion-bewilderment (Cohen's d = 0.53, Z = 39.00, p = 0.02), and increased commission error (Cohen's d = -0.59, t = -2.64, p = 0.02). Also, users of blue light smartphones experienced a longer time to reach dim light melatonin onset 50% (2.94 vs. 2.70 h) and had increases in body temperature, serum melatonin levels, and cortisol levels, although these changes were not statistically significant. Use of blue light LED smartphones at night may negatively influence sleep and commission errors, while it may not be enough to lead to significant changes in serum melatonin and cortisol levels.