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Beyond Aging, Sex and Insomnia Disorder Shape NREM Brain Oscillations
Nyissa A Walsh1,2,3,4,5, Aurore A Perrault1,4,6, Nathan E Cross1,4,7
1Sleep, Cognition, & Neuroimaging Lab, Department of Health, Kinesiology, & Applied Physiology, Concordia University, Montreal, Canada.
Sleep
|July 15, 2026
Summary
Chronic insomnia disorder (INS) disproportionately affects females. This study found that reduced spindle density and sigma power in female INS patients may explain their higher insomnia severity compared to males.
Area of Science:
- Neuroscience
- Sleep Medicine
- Chronobiology
Background:
- Chronic insomnia disorder (INS) is more common in older adults and females.
- Sex- and age-related neurophysiological differences in sleep markers like sleep spindles and slow-wave activity (SWA) may explain this vulnerability.
- Understanding these mechanistic differences is crucial for targeted INS treatments.
Purpose of the Study:
- To investigate the impact of sex and chronic insomnia disorder on sleep spindle and SWA characteristics.
- To examine neurophysiological markers of sleep quality beyond aging.
- To elucidate sex-specific mechanisms contributing to higher INS prevalence in females.
Main Methods:
- Polysomnography data from 222 adults (119 INS, 103 healthy sleepers) aged 18-82 were analyzed.
- Key metrics included spindle density, slow oscillation (SO) density, relative sigma power, and SWA during NREM sleep.
- Statistical analyses examined effects of age, group, sex, and their interactions, controlling for age.
Main Results:
- Age, INS, and sex independently influenced NREM oscillatory activity.
- INS was associated with reduced spindle and SO density.
- Females exhibited higher SWA overall, but sex differences in SWA were not significant within groups. Female INS patients had lower sigma power and spindle/SO density compared to male INS patients and female healthy sleepers.
Conclusions:
- Reduced sigma power in females with INS compared to males, and lower spindle/SO density compared to female healthy sleepers, may contribute to greater insomnia severity in females.
- These findings highlight sex-specific neurophysiological alterations in chronic insomnia disorder.
- Further research into sex-based mechanisms can inform personalized INS therapies.
Keywords:
EEGSexchronic insomniadeltagenderinsomnia disordersigmasleepslow oscillationslow wave activityspindleMore Related Videos
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