Cardiac Responses to Daily Threats and Challenges During Wakefulness and Sleep

This research examines cardiovascular response to everyday threats and challenges during wakefulness and sleep. Approximately eleven thousand people, who comprised a diverse sample ethnically but not socioeconomically, completed three weekly morning and evening surveys in which they indicated whether they expected and experienced threats and challenges that day. Participants also provided measures of blood pressure on morning surveys and provided measures of average heart rate during the day and resting heart rate when asleep via their WHOOP biometric capture device. Enrollment began in April, 2024 and data collection ceased in July, 2024. Results indicated that both threat and challenge were associated with higher blood pressure and higher average heart rate during the day. In contrast, when people were asleep, threat was associated with higher resting heart rate but challenge was associated with lower resting heart rate. These results suggest that the body achieves more restorative sleep in preparation for perceived challenges but not for perceived threats, raising the possibility that the greater stress associated with threats disrupts the body’s capacity for restorative sleep. The generalizability of these results to members of economically marginalized groups remains an open question.