Reallocations of Time Between Sleep, Sedentary Behavior, and Physical Activity and their Associations with 24-Hour Blood Pressure.

Background: The 24-hour activity cycle (sleep, sedentary behavior, light physical activity, moderate to vigorous physical activity) may have deleterious or beneficial associations with 24-hour blood pressure.

Purpose: Estimate the short-term associated changes in 24H-BP with acutely replacing 30 min/d from one behavior of the 24H-ACT to other behaviors in employed adults.

Methods: Participants (N=659) wore an ambulatory blood pressure monitor and two accelerometers (waist and wrist) to measure 24-hour blood pressure and the 24-hour activity cycle.

Results: Replacing 30 minutes of sedentary behavior with 30 minutes of sleep was associated with lower 24-hour mean systolic [ß=-0.32 mmHg per 0.5hr (95% CI: -0.58, 0.06)] and diastolic [ß=-0.31 mmHg per 0.5hr (95% CI: -0.50, -0.12)] blood pressure. Replacing 30 minutes of light physical activity with 30 minutes of sleep was associated with lower 24-hour mean systolic [ß=-0.30 mmHg per 0.5hr (95% CI: -0.62, 0.03,)] and diastolic blood pressure [ß=-0.34 mmHg per 0.5hr (95% CI: -0.58, -0.11,)]. No other time reallocations between 24-hour activity cycle behaviors were associated with changes in 24-hour blood pressure.

Conclusion: Replacing time in sedentary behavior or light physical activity with sleep may provide small short-term reductions in that day's 24-hour blood pressure.