Effects of Two Nights of Severe vs. Mild Sleep Restriction on Vertical Jump Performance in Physically Active Female Students

Partial sleep deprivation is common in sports, particularly before competitions. This study examined whether two nights of severe sleep restriction (<4 h/night), compared with mild sleep restriction (control), are associated with changes in SJ and CMJ in physically active female students. Twenty-three female students (<i>n</i> = 12 experimental; <i>n</i> = 11 control) were randomly assigned to their respective groups. The experimental group underwent two nights of severe sleep restriction (<4 h/night), while the control group experienced mild sleep restriction. Differences between groups were analyzed using Quade's nonparametric ANCOVA (sleep duration as covariate), and within-group pre-post changes were evaluated using paired-samples <i>t</i>-tests. No significant differences were found between groups after two nights in CMJ (<i>p</i> = 0.92) or SJ (<i>p</i> = 0.73) performance. Within the experimental group, SJ performance significantly decreased from the initial to the final assessment (<i>p</i> = 0.02), with a large effect size (d = -0.81). CMJ performance in the experimental group showed a non-significant decrease with a moderate effect size (d = -0.45). No significant differences or notable effect sizes were found in the control group (d = 0.01 to 0.23). Within-group results suggest that SJ decreased after severe sleep restriction, while CMJ changes were smaller and not statistically significant; between-group comparisons were not significant, and results appear sensitive to the analytical approach. These exploratory findings suggest that monitoring sleep before power-related tasks may be warranted. Coaches may consider monitoring sleep duration before high-intensity power training, as two nights of severe sleep restriction may be associated with reduced SJ performance.