Abstract / Summary
Objectives: Temperature-controlled sleep surfaces are used nightly by hundreds of thousands of people, yet cohort analyses show improved perceived sleep quality without matching objective change. Cohort means may mask benefits concentrated in those with the greatest baseline deficit. We asked whether objective changes in sleep and overnight cardiovascular function differ by baseline sleep performance. Methods: In this exploratory, retrospective, open-label study of 171 adults, wearable-derived sleep and overnight cardiovascular endpoints were compared between seven baseline nights and the first seven nights on a temperature-controlled sleep surface (Orion Sleep System). Participants were stratified by baseline performance separately for each endpoint. Results: At the cohort level, total sleep time rose 7.3 minutes (p = 0.01, not significant), average heart rate fell 1.79 bpm (95% CI -2.25 to -1.34) and minimum heart rate 1.75 bpm (95% CI -2.18 to -1.33; both p < 0.001), and HRV rose 3.25 ms (95% CI 1.33 to 5.17, p = 0.001). Effects were baseline-dependent. In the most-deficient quartile for each endpoint, total sleep time rose 33.5 minutes (9.6%; 95% CI 21.5 to 45.5), REM 13.6 minutes (19.4%; 95% CI 8.6 to 18.6), deep sleep 4.4 minutes (13.1%; 95% CI 2.0 to 6.9), and HRV 4.7 ms (15.6%; 95% CI 2.2 to 7.2); wake after sleep onset fell 16.3 minutes (26.0%; 95% CI -23.0 to -9.6) in the most fragmented quartile (all p < 0.001). Conclusion: Objective gains were largest where the baseline deficit was greatest.