Comparison of intervention and baseline nights
No significant differences between intervention night F and corresponding baseline night BF were found. All parameters were statistically identical in all sleep stages indicating that F has no or a very small impact on cardiac autonomic functioning. Comparing R with baseline BR, several significant differences regarding HR and HRV were found, suggesting a greater impact of R on the autonomic modulation of the heart (see Fig. The higher HR, lower SDNN and lower pNN50 during the sleep restriction night compared to the corresponding baseline might reflect a shift towards increased sympathetic activity with less parasympathetic activity during a night with sleep restriction, especially for the light sleep stages and wake times.