# Impaired slow-wave sleep accounts for brain aging-related increases in anxiety

## TL;DR

This study shows that poor deep sleep in older adults is linked to increased anxiety due to brain changes, highlighting a key mechanism for mental health decline in aging.

## Contribution

The study identifies impaired slow-wave sleep as a novel mechanism linking brain aging to increased anxiety in older adults.

## Key findings

- Impaired slow-wave activity during sleep predicts higher anxiety in older adults.
- Brain atrophy in emotion-processing regions is associated with reduced slow-wave activity.
- Intact slow-wave activity may preserve emotional stability despite brain aging.

## Abstract

Aging doesn’t just dull our memories; it destabilizes our emotions while further impairing sleep quantity and NREM sleep quality. Emotional dysregulation and anxiety symptoms in older adults accelerate their risk of cognitive decline and dementia, yet the underlying mechanisms remain largely unclear. In young adults, reductions in deep sleep, specifically the loss of slow wave activity (SWA) during non-REM sleep, impair the brain’s ability to regulate anxiety overnight. This raises a testable hypothesis: Does age-related decline in SWA contribute to increased anxiety symptoms in older adults? We test this hypothesis in 61 cognitively healthy older adults (>65 y) experiencing varying levels of anxiety. Each participant underwent polysomnography-recorded sleep in the lab, followed by a structural MRI the next morning to assess atrophy in anxiety-sensitive brain regions. A subset of 24 participants was tracked longitudinally over 4 ± 2.02 years. The findings were consistent. Greater impairment in nighttime SWA predicted higher next-day anxiety in older adults, both at baseline and at follow-up. Brain imaging revealed the mechanism: atrophy in key emotion-processing regions was associated with reduced capacity to generate robust slow waves needed for overnight anxiety regulation. Critically, mediation analysis showed that impaired SWA fully accounted for the relationship between regional atrophy and disrupted overnight anxiety regulation. These findings suggest that even in the presence of age-related brain atrophy, intact SWA may preserve emotional stability by rescuing the brain’s nightly emotional recalibration process, protecting mental health in aging populations.

Aging is not just a matter of cognitive decline but of mental health decline. This study reveals that in healthy older adults, anxiety is scaled with impaired slow-wave activity during sleep, accompanied by atrophy in emotion-processing brain regions.