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Free keywords:
co-sleep, REM sleep, synchronization, bed-sharing, physiological coupling, sociality, chronotype, relationship quality
Abstract:
Background/Objectives: Sharing the bed with a partner is common among adults and
impacts sleep quality with potential implications for mental health. However, hitherto findings are contradictory and particularly polysomnographic data on co-sleeping couples are extremely rare. The present study aimed to investigate the effects of a bed partner's presence on individual and dyadic sleep neurophysiology.
Methods: Young healthy heterosexual couples underwent sleep-lab-based polysomnography of two sleeping arrangements: individual sleep and co-sleep. Individual and dyadic sleep parameters (i.e., synchronization of sleep stages) were collected. The latter were assessed using cross-recurrence quantification analysis.
Additionally, subjective sleep quality, relationship characteristics, and chronotype were monitored. Data were analyzed comparing co-sleep vs. individual sleep. Interaction effects of the sleeping arrangement with gender, chronotype, or relationship characteristics were moreover tested.
Results: As compared to sleeping individually, co-sleeping was associated with about
10% more REM sleep, less fragmented REM sleep (p = 0.008), longer undisturbed REM
fragments (p = 0.0006), and more limb movements (p = 0.007). None of the other Sleep stages was significantly altered. Social support interacted with sleeping arrangement in a way that individuals with suboptimal social support showed the biggest impact of the sleeping arrangement on REM sleep. Sleep architectures were more synchronized
between partners during co-sleep (p = 0.005) even if wake phases were excluded (p =
0.022). Moreover, sleep architectures are significantly coupled across a lag of ± 5min.
Depth of relationship represented an additional significant main effect regarding
synchronization, reflecting a positive association between the two. Neither REM sleep nor synchronization was influenced by gender, chronotype, or other relationship
characteristics.
Conclusion: Depending on the sleeping arrangement, couple's sleep architecture and
synchronization show alterations that are modified by relationship characteristics. We
discuss that these alterations could be part of a self-enhancing feedback loop of REM
sleep and sociality and a mechanism through which sociality prevents mental illness.
