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Naps and circadian rhythms in postmenopausal women
In-Young Yoon1, Daniel F Kripke, Jeffrey A Elliott
1Department of Psychiatry, 0667, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0667, USA.
Summary
Postmenopausal women
Area of Science:
- Sleep science
- Chronobiology
- Gerontology
Background:
- Investigated napping patterns in postmenopausal women.
- Examined links between naps, circadian rhythms, and nocturnal sleep.
- Compared sleep in depressed versus healthy women.
Purpose of the Study:
- To evaluate napping patterns and their relationship with circadian rhythms and nocturnal sleep in postmenopausal women.
- To compare sleep and napping behaviors between depressed and healthy postmenopausal women.
Main Methods:
- Included 436 postmenopausal women (ages 50-81).
- Utilized wrist-activity monitors, sleep logs, and urinary melatonin metabolite (6-sulfatoxymelatonin [aMT6s]) measurements.
- Conducted psychiatric interviews using the Structured Clinical Interview for DSM-IV Axis I Disorders.
Main Results:
- No significant differences in sleep or napping between depressed and healthy women.
- Identified three main napping peaks: near bedtime, 8-9 hours post-wake, and 2 hours post-wake.
- Evening naps correlated with earlier wake-up times and advanced aMT6s acrophase (melatonin rhythm marker).
Conclusions:
- Evening napping in postmenopausal women may indicate advanced circadian rhythms.
- The association between evening napping and earlier wake times could be a circadian or homeostatic effect.