Moderate-intensity continuous exercise preserves sleep quality, while high-intensity intermittent exercise disrupts...

This study aimed to explore the effects of a single bout of moderate-intensity continuous exercise (MICE) and high-intensity intermittent exercise (HIIE) on sleep in inactive female healthcare workers with mild sleep impairment during continuous night-shifts. A total of 14 subjects (mean age: 31.8 ± 8.3 years) were randomized to either a MICE (70 ~ 75% of the maximum heart rate (MaxHR) for 47 min), HIIE (90 ~ 95% of the MaxHR for 4 min and 50 ~ 70% for 3 min, for 4 rounds, total 28 min), or the quiet-rest control, 14 h before undertaking a continuous night shift. Sleep quality was assessed subjectively by a single question score, and objectively by ActiGraph for one night before and 3 sleeps after exercise with a heart rate variability monitor. After the intervention, MICE resulted in a significant improvement in subjective sleep quality (P = 0.035), earlier bedtime (P < 0.001), and more total sleep time (P = 0.028) compared with the control trial (CTL). Compared with MICE, the HIIE had a greater reduction in sleep efficiency by 7.39% (P = 0.010) and had a greater increase in wake after sleep onset percentage (increase 10%, P = 0.049), sleep fragmentation index (increase 2%, P = 0.001), and a modest increase in mean activity during TIB (increase 35.49, P = 0.035). Regarding HRV, HIIE trial showed an increased LF/HF following intervention while CTL decreased. A single session of MICE preserved subjective sleep quality and promoted an earlier bedtime prior to the first night shift for female healthcare workers experiencing mild sleep disturbances during night shifts. However, compared with MICE, a single session of HIIE had a detrimental effect on sleep maintenance and increased sympathetic activity, even affecting sleep before the second night shift.Trial registration NCT06638359. Registered 15 October 2024 Retrospectively registered, https://register.clinicaltrials.gov .