0957 Sleeping for one week on a temperature-controlled mattress cover improves slow wave sleep, heart rate, and heart rate variability

Abstract

Abstract Introduction Body temperature should be tightly regulated for optimal sleep. A decline in core temperature during sleep onset can increase slow wave sleep (SWS) and decrease heart rate (HR). Passive solutions such as high-heat capacity mattresses are difficult to maintain temperature control during sleep. Thus, we examined how sleeping on an active temperature-controlled mattress cover (TCMC; i.e., the Eight Sleep Pod) for one week affected sleep and cardiovascular health. Methods 49 participants [24 men, 25 women; mean±SD (range): age = 34.4±11.5 (21.8-64.6) years] slept for 16 nights each (784 total nights) with TCMC temperature-control off (OFF) for the first week as baseline, TCMC temperatures on (ON) at their desired temperatures for the second week, and TCMC OFF for two nights. Participants wore a home sleep test device (HST) for eight nights total: four nights during each OFF and ON for ground truth sleep-staging. Participants wore a Fitbit device throughout the study to collect nightly HR and heart rate variability (HRV). Paired t-tests compared each participant’s sleep and HR/HRV for TCMC ON vs. OFF, separating for biological sex and TCMC temperature. A multiple linear regression was used to evaluate the percent change in SWS from OFF to ON. Results Four factors explained 64% of the variance in the percent change in SWS from OFF to ON (r2=0.64; P< 0.001): participants’ baseline SWS during OFF, age, average mattress-cover temperature, and sex. Men sleeping at cooler temperatures (< 26°C) increased SWS by 17 min (P=0.0001; cohen’s-d=0.65), decreased HR by 1.5 beats/minute (P=0.007, cohen’s-d=0.20), and increased HRV by 13% (P=0.045; cohen’s-d=0.23). Women’s sleep was unaffected by TCMC ON (all P>0.05); however, sleeping at warmer mattress-cover temperatures (>27°C) decreased HR by 1.5 beats/minute (P=0.021; cohen’s-d=0.18). Conclusion Sleeping on an active temperature-controlled mattress cover at cooler temperatures significantly improved SWS in males, especially those with below-average SWS at baseline and increasing age. One week of sleeping on the TCMC improved HR in both sexes similar to exercise-training. Support (if any) Eight Sleep, Inc.