Two-thirds of adults share their bed with a partner, yet few studies have measured how this impacts sleep and recovery (Ref). We analyzed over 238,000 nights of real-world sleep data in more than 4,000 adults who slept with and without their partner. We found that sleeping with a partner increases heart rate variability (HRV) by 8% on average compared to sleeping alone. The most striking finding? Women experience nearly double the cardiovascular benefit of men when sharing a bed with their partner.
Key Takeaways
- Sharing a bed with a partner significantly increased HRV by 8% on average, with women showing a 10% improvement compared to 6% in men.
- Total sleep time significantly increased by ~6 minutes per night when sleeping with a partner for both men and women.
- Importantly, these cardiovascular benefits occurred from even just one night of sleeping with a partner.
We analyzed over 238,000 nights of real-world sleep data in 4,000+ Eight Sleep members
To understand how sleeping with a partner influences sleep and cardiovascular recovery, we analyzed 238,000 nights of sleep from 4,043 adults who alternated between sleeping alone and sleeping with a partner. To be included in the analysis, each person had at least 10 partner nights and 10 solo nights, allowing us to compare how the same individual slept under both conditions.
For the nights sleeping with vs. without a partner, we analyzed heart rate (HR), heart rate variability (HRV), total sleep time, sleep stages, and snoring data.
On average, people slept with their partner about 67% of nights, reflecting how common sleeping with a partner is in everyday life.
The results are clear: sharing a bed with a partner improved cardiovascular recovery, especially for women
Sharing a bed significantly increased HRV by 8% on average
The clearest physiological signal we observed was in HRV. When sleeping with a partner, HRV significantly increased by 8% on average. This improvement represents meaningful enhancement in overnight cardiovascular recovery and parasympathetic nervous system activity.
Higher HRV during sleep signals better stress resilience, next-day readiness, and long-term cardiovascular health. Changes in HRV indicate how well-rested you are, both physically and mentally. For context, HRV declines naturally with aging across both sexes, making an 8% improvement from partner sleeping a substantial benefit (Ref).
Women show larger HRV gains compared to men when sleeping with a partner
Women experienced a 10% HRV increase when co-sleeping, compared to 6% in men (see Figure 1). This sex difference suggests that women may experience stronger parasympathetic activation or stress-buffering effects from sleeping near their partner.
The mechanism behind this difference isn’t yet clear. It may relate to differences in autonomic regulation, stress perception, or social attachment patterns, all areas that warrant further investigation (Ref; Ref). These observed benefits may also reflect the calming effects of pre-sleep routines and interactions that occur when couples share a bed.
Figure 1: Percent change in HRV when sleeping with a partner vs solo. Bars represent the average of all participants per sex. The values listed above the bars are the mean % change by sex (women on the left, men on the right).
Total sleep time increased modestly but consistently
Partner sleeping significantly increased total sleep time by ~6 minutes on average for both men and women. However, changes in HR, sleep stages, and snoring frequency were not meaningfully different physiologically.
How often someone shared a bed did not substantially change these effects
Interestingly, we found that the number of nights per week partners shared a bed did not change the magnitude of the HRV effect. This finding suggests the benefit comes from partner presence itself, rather than long-term adaptation or habituation to partner sleeping.
What this means for sleep health
These findings challenge the assumption that sharing a bed with a partner necessarily disrupts sleep quality. Instead, they reveal that sharing a bed with a partner can meaningfully support cardiovascular recovery and sleep duration, particularly for women. This may be because the Eight Sleep Pod’s dual-zone temperature control helps each partner maintain a comfortable sleep environment throughout the night, promoting more consistent and restorative sleep.
For individuals optimizing sleep and recovery, these data provide evidence that partner sleeping arrangements can be a net positive for cardiovascular health.
Interested in optimizing recovery for you and your partner? Learn how the Pod’s dual-zone temperature control helps couples sleep better at eightsleep.com.
Appendix
Statistical analyses used FDR-corrected paired t-tests for partner versus solo sleeping differences, sex effects with Welch’s t-tests, and Pearson correlations assessed relationships between frequency of sleeping with a partner and objective changes. Significance was defined as p<0.05. All reported effects represent population-level averages; individual responses varied.
