Physical Activity as a Tool to Improve Sleep Quality for Secure Psychiatric Inpatients: A Feasibility Study.

People with a severe mental illness (SMI) often experience insomnia and disrupted sleep-wake cycles. Daytime physical activity (PA) can retrain the sleep/wake cycle, but PA engagement is often markedly low in SMI. It is hypothesised that frequent, intermittent, short bouts of daytime PA can improve sleep outcomes in SMI. Twenty-two inpatients from a secure psychiatric hospital (39.95 ± 16.87 years, 16 male) were recruited for a 10-week PA intervention involving 3 × 10-min bouts of self-selected intensity PA/day, 5 days/week. Feasibility (primary outcome) was examined by assessing recruitment, outcome measure completion, trial adherence, and participant retention. At baseline, mid-point, and post-intervention, inpatients completed surveys, including the insomnia severity index (ISI) and wore the Motionwatch8 actigraph for 7 days to record sleep and PA data (including sleep efficiency (SE), total sleep time (TST), and moderate-to-vigorous PA (MVPA)). Outcome completion ranged from 67% to 91%. Mean trial adherence was 22% (range 2%-77%). Participant retention was 100%. Pre-to-post intervention, ISI scores decreased from 12.14 (SD = 4.98) to 11.38 (SD = 6.18) (t (20) = 0.65, p = 0.53). Time to bed and time of falling asleep both advanced (p > 0.05). Mid-point of sleep (M = 38 min, SE = ≥ 15.93 min, p = 0.01) and wake time (M = 34 min, SE = 15.92 min, p = 0.02) significantly advanced. MVPA increased by 17 min/day (T = 1.17, p > 0.05). Other sleep indices (e.g., TST, SE) did not change significantly. Outcome completion and participant retention rates were high; trial adherence was low. Increasing intermittent PA can reduce psychiatric inpatients' insomnia symptoms and advance sleep phase. Sample variance and participant-researcher rapport are discussed. Findings highlight the beneficial effect of short bouts of PA on sleep, providing scaffolding for future trials.