# The impact of bedtime alignment on sleep health in older couples: gender-sensitive analysis

## TL;DR

This study shows that older couples who go to bed at similar times have better sleep quality, especially for women, suggesting that synchronized bedtimes improve sleep health.

## Contribution

The study introduces a gender-sensitive analysis of how bedtime alignment affects longitudinal sleep outcomes in older couples.

## Key findings

- Couples with synchronized bedtimes had the best sleep quality, while those with misaligned bedtimes had the worst.
- Women in misaligned groups experienced progressive sleep deterioration over 8 years, unlike men.
- Synchronized bedtimes are a modifiable factor for improving sleep health in older couples.

## Abstract

Although most couples share a bed, current interventions rarely consider dyadic sleep patterns.

We investigated whether bedtime alignment between partners affects longitudinal sleep outcomes in older couples, with particular attention to gender differences.

Based on the temporal relationship between partners’ bedtimes and the earlier sleeper’s sleep onset latency, 859 couples (1718 individuals) aged ≥60 years were classified into 5 mutually exclusive bedtime alignment groups. Pittsburgh Sleep Quality Index (PSQI) scores, sleep onset latency and sleep efficiency were compared using analysis of variance and multivariate analysis of covariance. Both cross-sectional and 8-year longitudinal trajectory analyses were conducted.

Bedtime alignment significantly affected sleep outcomes (P < 0.001, Pillai’s Trace = 0.37, F
24, 3352 = 14.04, P < 0.001, η
2
P = 0.09). Couples with synchronised bedtimes demonstrated excellent sleep quality, whereas those with bedtime differences less than the earlier sleeper’s sleep onset latency exhibited the worst. The earlier sleepers in such couples experienced longer sleep onset latencies (53.4 ± 46.8 min) and greater sleep quality impairment (PSQI = 7.9 ± 4.1). The 8-year trajectory analysis revealed gender-specific vulnerability: only women in misaligned groups experienced progressive sleep deterioration over time (5.84 ± 8.42 min/year increase in sleep onset latency, P < 0.001; 1.27 ± 1.93%/year decrease in sleep efficiency, P < 0.001), whereas men maintained stable sleep parameters regardless of alignment.

Bedtime alignment represents a modifiable determinant of sleep health in older couples, with synchronised bedtimes providing optimal outcomes and partial sleep onset overlap creating disruption. This particularly benefits women, who show progressive deterioration with misalignment. These findings support the development of gender-informed, couple-based interventions for sleep disorders.