Contributed by Megan Holm, M.S. & Sofie Jacobsen, M.S.
Pregnancy increases demand on the body: resting heart rate (RHR) increases, heart rate variability (HRV) decreases, sleep becomes more fragmented, and deep sleep declines (source, source, source, source). All of these changes impact morning refreshedness, daytime functioning, and decision-making (source).
We wanted to know: does sleeping on the Pod during pregnancy ease any of these cardiovascular (HR/HRV) and sleep changes?
To answer this question, we analyzed data from over 100 women who reported pregnancies while sleeping on the Pod. We found that sleeping on the Pod during pregnancy and postpartum eases strain during pregnancy and postpartum, compared to pregnant women not sleeping on the Pod. Main findings are highlighted below and detailed findings can be found here.
Key takeaways
Pregnant and postpartum women sleeping on the Pod have more favorable recovery and sleep metrics, compared to women not sleeping on the Pod. Specifically, we found that:
- During the third trimester, Pod members have strong recovery: RHR is 3 bpm lower and HRV is 2 ms higher, both on average.
- Pod members sleep an average 12 minutes more, including 7 more minutes of deep sleep, each night during the third trimester.
- During postpartum, Pod members recover better: RHR is 3 bpm lower and HRV is 16 ms higher. The Pod also protects postpartum sleep; members have 15 minutes more sleep each night, on average.
To date, this is the most comprehensive study exploring pregnancy changes on a nightly basis and introduces brand new pregnancy and postpartum-period metrics, like sleep temperature preferences, deep sleep, and REM sleep. The study also expands the timeframe in which postpartum recovery is studied, increasing it from six weeks to six months, to be more comprehensive than ever before.
Pregnancy strains the body
Pregnancy makes the body work harder, which has been quantified with wearables among women not using the Pod (source, source, source, source). Resting heart rate climbs steadily into the third trimester, because the heart pumps more blood to meet the fetus’s rising oxygen demand (source). HRV, which reflects nervous-system regulation (source), falls over the same time period (source). Sleep suffers too: deep sleep declines, nighttime awakenings increase, and total sleep time drops sharply in the early postpartum period (source, source, source, source, source).
Sleeping on the Pod eases pregnancy and postpartum strain on the body
Compared to pregnant and postpartum women not sleeping on the Pod, the size of the cardiovascular and sleep changes is smaller among Pod members. This indicates that sleeping on the Pod reduces pregnancy- and postpartum-related strain (see Table).
Table. Comparison of sleep and cardiovascular recovery changes across pregnancy and the postpartum period between women using vs. not using the Pod.
Note. “Average change among women not using the Pod” reflects the mean of available values reported across four large-cohort studies using Apple Watch, Oura Ring, WHOOP, and Fitbit. Not all studies report every metric, so we calculated the mean of all reported values when available. Eight Sleep Pod values are from this study. RHR = resting heart rate; HRV = heart rate variability. The bolded values indicate where the size of the change observed among Pod members is more favorable than the average change among women not using the Pod.
Why sleeping on the Pod reduces pregnancy and postpartum strain
The Pod improves sleep quality, objective sleep metrics, and cardiovascular recovery in younger and older non-pregnant adults (source, source, source, source). A large majority of these improvements could be due to the fact that the Pod lowers core body temperature during sleep (source). Therefore, the Pod is likely helping pregnant and postpartum women via core body temperature cooling during sleep, which is in turn improving cardiovascular recovery, deep sleep, and total sleep time.
Check out the full results from this study
The full study introduces many new findings captured by the Pod, including temperature changes across pregnancy and postpartum. All of the findings are currently available via our blog and as a preprint.
Appendix
Eight Sleep members were recruited via email and contributed data from 12 weeks before conception through 24 weeks into the postpartum period, covering approximately 46,000 nights (n= up to 101 pregnancies). Six analysis periods were defined, relative to each participant’s self-reported delivery date: a 12-week pre-pregnancy baseline, three typically-defined pregnancy trimesters, and an early and late postpartum trimester (i.e. 0–12 and 13–24 weeks after delivery). All contrasts were made against the pre-pregnancy baseline using linear mixed-effects models with the Holm step-down correction for multiple comparisons. Significance was defined as p<0.05.
This is a retrospective, observational study with no non-Pod control group. All reported effects represent cohort-level averages; individual responses varied. The study was reviewed and approved by Sterling IRB. Informed consent was waived given the retrospective design, pre-existing de-identified data, and minimal risk to participant privacy.
