Active Bed Microclimate Regulation Modulates Sleep Architecture, Autonomic, and Central Nervous System Activity during Sleep
Skin temperature and bed microclimate are established modulators of human sleep, but most prior work has relied on passive thermal materials. We used a smart bed capable of heating or cooling the microclimate to investigate how six temperature settings affect sleep architecture, autonomic activity, and electroencephalographic (EEG) activity. Eighteen adults (9 male, 9 female; mean age 44.5 years) completed two overnight polysomnography sessions with bed temperature assigned via Latin-square counterbalancing across three-hour segments of high cooling, medium cooling, low cooling, off, low heating, and medium heating. Mixed-effects regression models evaluated manipulation checks on induced thermal changes, the probability of sleep versus wake, and the probability of each sleep stage (N1, N2, N3, REM), while secondary analyses assessed sleep deepening, heart rate, and EEG spectral power. Temperature manipulations significantly affected sleep and physiological outcomes. All five active settings shifted sleep toward greater depth, increasing the odds of slow-wave sleep (odds ratios 1.21 to 3.65, largest for high cooling) and reducing the odds of light non-rapid eye movement sleep relative to off. Heating accelerated early sleep deepening relative to cooling without significantly altering sleep onset latency, whereas cooling produced a graded reduction in heart rate. EEG analyses revealed distinct cortical signatures for heating and cooling conditions. These findings demonstrate that active bed microclimate regulation modulates sleep architecture, autonomic activity, and cortical activity during sleep. The nonlinear pattern of effects suggests thermal "sweet spots" that may vary across the night and individuals, supporting the development of individualized programmable temperature-regulation strategies for sleep optimization.