Quantifying Sleep-Wake Rhythms in the Hospital Environment with Digital Technologies

Postoperative clinical care is prone to circadian desynchronization that, in turn, may influence health outcomes. We collected 1.8 million data points using 11 remote sensors during preoperative, in-hospital and post-discharge settings in 13 elective cardiac surgery patients. We found that room traffic continued during nighttime with ≥1 visit/h. Sound levels exceeded the recommended 45 dBA threshold (51.9±3.3 versus 48.3±4.2 dBA during nighttime). Brightness dropped at night (89.9±87.7 to 3.7±9.8 lux), but bright light exposures occurred. Ambient room temperature lacked sleep-inducing diurnal variability. Behavioral-physiological rhythms were disrupted (decreased amplitude of heart rate variability; unadjusted-p-value=0.03) and phase-shifted during hospitalization. Time awake during night hours increased from 10.7±7.9% preoperatively to 34.8±29.1% in-hospital (unadjusted p-value=0.0098). Cognitive function scores decreased (26.8±2.8 points preoperatively to 24.7±3.9 points in-hospital) with 31% of patients developing transient mild impairment. These data will inform the design of a controlled trial seeking to modify circadian/diurnal disruptors to enhance patient outcomes.