Active temperature regulation during sleep decreased sleeping heart rate by 1.8 bpm, increased heart rate variability by 3.6 ms, and reduced core body temperature by 0.16°C (all P<0.001).
Does active temperature regulation during sleep improve circadian rhythm, cardiovascular recovery, and sleep composition in older adults?
Active temperature regulation during sleep lowers core body temperature and improves heart rate variability and sleep composition in older adults.
Effect estimate: Mean difference: HR -1.8 bpm, HRV +3.6 ms, Tc -0.16°C
p-value: p=<0.001
Abstract Introduction Sleep quality declines with age, potentially resulting from a blunted circadian rhythm of core body temperature (Tc), which can reduce deep sleep and cardiovascular recovery. Cooling during early hours of sleep with high-heat capacity mattresses lowers Tc and heart rate (HR) and increases deep sleep in postmenopausal women, suggesting whole-night active temperature regulation (ATR) might further enhance Tc rhythms and sleep-related cardiovascular recovery. We evaluated how continuous ATR affects circadian rhythm, cardiovascular recovery, and sleep composition in older adults. Methods 90 participants (n=60 postmenopausal women and n=30 age-matched men; mean±SD: 55±5 y) slept on the Eight Sleep Pod, a mattress cover enabling ATR throughout the night, for 7 nights each with ATR OFF vs. ON. Sleep stages, HR, and heart rate variability (HRV) were measured nightly with smart rings, and Tc was measured via gastrointestinal pills. Linear mixed-effects models analyzed nightly outcomes (means±SE reported below), Pearson's correlation coefficient and linear models analyzed participant-level changes between ATR conditions, and single-harmonic cosinor analysis analyzed Tc rhythms. Results On average, ATR decreased sleeping HR by 3% (-1.8±0.3 bpm), increased HRV by 11% (+3.6±0.6 ms), and reduced Tc by -0.16±0.01°C. ATR ON lowered Tc mesor, the 24-hour average, by -0.07±0.01°C and increased Tc amplitude by +0.07±0.02°C (all P 0.001), indicating improved circadian rhythm. Larger decreases in Tc from ATR OFF to ON correlated with greater HR improvements (r=0.34, P=0.037). Using cooler ATR temperatures corresponded with larger HRV increases (r=-0.31, P=0.004). ATR ON improved sleep composition for participants with poor sleep composition at baseline (i.e., average light sleep 65.0%, deep sleep 13.7%, REM sleep 21.3% or wake after sleep onset 9.5%; all P 0.05). Conclusion To our knowledge, this is the first evidence that ATR can lower Tc in adults 55+ years, thereby improving Tc circadian rhythm. These circadian-rhythm improvements enhanced cardiovascular recovery and sleep composition. As sleep quality is reduced with aging, ATR during sleep can be an excellent non-pharmacological solution to restore sleep health in older adults. Support (if any) This research was funded by Eight Sleep Inc.
Jacobsen et al. (Fri,) conducted a other in Older adults (n=90). Active temperature regulation (ATR) via Eight Sleep Pod vs. ATR OFF was evaluated on Sleeping heart rate, heart rate variability, and core body temperature (Mean difference: HR -1.8 bpm, HRV +3.6 ms, Tc -0.16°C, p=<0.001). Active temperature regulation during sleep decreased sleeping heart rate by 1.8 bpm, increased heart rate variability by 3.6 ms, and reduced core body temperature by 0.16°C (all P<0.001).