Effects of acute morning and evening exercise on subjective and objective sleep quality in older individuals with insomnia

•Acute morning exercise may moderately improve objective sleep in older adults.•Effect of acute exercise was observed during later part of nocturnal sleep.•Effect of acute physical exercise differs between types of insomnia.

ObjectivesThe aims of this study were to compare the effects of acute morning or evening exercise on nocturnal sleep in individuals with two subjective insomnia symptoms: difficulty in initiating sleep (DIS), and early morning awakening (EMA), separately for the first vs the second halves of the night.MethodsOlder individuals (55-65 years old) with DIS (N = 15) or EMA (N = 15) and age- and sex-matched controls (N = 13) participated in this non-randomized crossover study. Participants were assigned to two exercise conditions (morning exercise and evening exercise) in counterbalanced order following the baseline condition with a two-week interval between conditions. A single session of aerobic step exercise was performed during each exercise condition. Nocturnal polysomnography was carried out to evaluate objective sleep quality. Patient global impression of change scale scores for nocturnal sleep were obtained to subjectively evaluate the different groups.ResultsAcute physical exercise did not improve subjective sleep quality. Morning exercise decreased the number of stage shifts over the whole night. The arousal index and the number of stage shifts were decreased especially during the second half of the night in all groups. Furthermore, morning exercise decreased the number of wake stages during the second half of the night in the DIS group, but not in the EMA group.ConclusionsAcute morning exercise can improve nocturnal sleep quality in individuals with difficulty initiating sleep, especially during the later part of the night.