In many countries, sharing a bed with a partner is common. Yet research on the relationship between bed sharing and sleep quality is both scarce and contradictory. Most studies have compared co-sleeping with individual sleep in couples by measuring body movements alone. dr. Henning Johannes Drews of the Center for Integrative Psychiatry (ZIP), Germany and colleagues overcame these limitations by also assessing sleep architecture in bed-sharing couples.
Researchers conducted the study on 12 young, healthy, heterosexual couples who spent four nights in the sleep lab. They measured sleep parameters in both the presence and absence of the partner using dual simultaneous polysomnography, which is a “highly exact, detailed and comprehensive method of recording sleep on many levels – from brain waves to movements, breathing, muscle tone, movements, heart activity.” says Dr. Drews. In addition, the participants completed questionnaires designed to measure relationship characteristics (e.g., relationship duration, degree of passionate love, relationship depth, etc.)
The results showed that REM (Rapid-Eye Movement) sleep is both increased and less disrupted in couples who sleep together compared to when they sleep individually. This finding is particularly relevant as REM sleep, which is associated with vivid dreams, has been associated with emotion regulation, memory consolidation, social interactions, and creative problem solving.
The team also found that couples synchronize their sleep patterns when they sleep together. This synchronization, which is not linked to partners disturbing each other at night, is positively associated with relationship depth. In other words, the higher the participants rated the significance of their relationship with their lives, the stronger the synchronization with their partner.
Interestingly, researchers found increased limb movement in bed-sharing couples. However, these movements do not disrupt sleep, which remains unchanged. dr. Drew states that "You could say that while your body is a bit unmanageable when you sleep with someone, your brain is not."
Despite the small sample size and explorative nature of some of the analyses, this study advances our understanding of couples' sleep and its potential implications for mental health. dr. Drews adds that "sleeping with a partner may even give you an extra boost in mental health, memory and creative problem-solving skills."
