Vulnerability and resistance to sleep disruption by a partner: A study of bed-sharing couples

Objectives: Methods for analyzing sleep as a dyadic behavior remain relatively unexplored. We aimed to (1) characterize how bedpartners influence each other's sleep, and (2) identify factors that predict sensitivity to wake transmission between bedpartners. Design: Cross-sectional study. Setting: Community members in Melbourne, Australia. Participants: Fifty-five couples without sleep disorders, aged 18-72 years. Measurements: Participants completed the Morningness-Eveningness Questionnaire, reduced version. Habitual sleep/wake patterns were monitored for seven nights via actigraphy and sleep diary. Epoch-by-epoch sleep/wake concordances (shared sleep/wake minutes), number of transmissions received (number of awakenings immediately preceded by bedpartner wakefulness), percent transmissions received (percentage of total awakenings that were transmissions), transmissibility (percentage of all bedpartner awakenings transmitted), and percent minutes resistant to transmission (percentage of bedpartner's wake minutes that an individual slept), were calculated. Mixed-effects modeling assessed predictors of dyadic sleep. Results: We described rates of sleep concordance (M = 66.8% ± 6.8%), wake concordance (M = 6.8% ± 3.1%), number of transmissions received (M = 6.0 ± 2.7), percent transmissions received (M = 18.9% ± 7.5%), transmissibility (M = 20.0% ± 6.2%), and percent minutes resistant (M = 52.1% ± 13.6%). Average couple-level percent transmissions received were highest and percent minutes resistant lowest in couples who had similar bedtime (within 30 minutes), compared to couples with greater differences in bedtime. Conclusions: Wake transmission is a useful metric of dyadic sleep, which varies according to relative bedtimes, and chronotypes of bedpartners. Higher wake transmissions for couples with similar bedtimes suggest dyadic preferences for shared bedtimes may be due to psychosocial benefits of shared sleep timing, rather than minimization of bedpartner-driven sleep disruption.