The Impact of Restricting Sleep Duration on Physical Activity: Secondary Analysis of a Randomized Crossover Study

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, p < .001, ηp2 = 0.934, and hourly comparisons, F(1, 166) = 30.47, p < .001, ηp2 = 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 < .01 in all cases) when controlling for other factors. Exploratory analysis showed the PA effects of SR manifested via reductions in PA intensity with concurrent increases in the proportion of time considered as sedentary. Conclusions: SR significantly lowered PA by around 7%, characterized by reduced intensity and elevated sedentary behavior in a naturalistic setting. Objetivos: Este estudio investigó el impacto causal de los niveles de sueño en la actividad física (PA, por sus siglas en inglés) de los participantes en condiciones reales. Métodos: Realizamos un análisis secundario de los datos de PA de 146 adultos jóvenes utilizando un diseño cruzado aleatorio: se evaluaron semanas de sueño restringido (5-6 horas/noche) y bien descansado (8-9 horas/noche), con un periodo de lavado de una semana de por medio. El sueño y la actividad se indagaron mediante actigrafía de grado de investigación. El análisis de datos de PA involucró medidas repetidas de ANOVA y técnicas de regresión. Resultados: Los planes de análisis y las hipótesis fueron pre registrados antes del análisis de los datos. El tratamiento de restricción del sueño (SR, por sus siglas en inglés) asignado exógenamente redujo el sueño nocturno en un prome