Health Psychology, Vol 43(8), Aug 2024, 561-569; doi:10.1037/hea0001360
Objectives: This study investigated the causal impact of sleep durations on participants’ physical activity (PA) in real-world conditions. Method: We performed a secondary analysis of PA data from 146 young adults using a randomized crossover design: both restricted (5–6 hr/night) and well-rested (8–9 hr/night) sleep weeks were assessed, with a washout week in between. Sleep and activity were tracked via research-grade actigraphy. Data analysis of PA involved repeated-measures analysis of variance (ANOVA) and regression techniques. Results: Analysis plans and hypothesis were preregistered before data analysis. The exogenously assigned sleep restriction (SR) treatment reduced nightly sleep an average of 92.65 min (± 40.44 min) compared to one’s well-rested sleep treatment. The impact of SR on PA was substantial, leading to a 7% reduction in average hourly PA: 18,081.2 (well-rested) versus 16,818.2 (restricted sleep). Significant findings were revealed in daily, F(1, 6) = 84.37, pp² = 0.934, and hourly comparisons, F(1, 166) = 30.47, pp² = 0.155. Further, sensitivity analysis using a variety of regression specifications also found that exogenously assigned SR decreased average wake-hour activity counts by approximately 4.4%–4.7% (p