BACKGROUND: Sleep and circadian interventions (e.g. interventions aimed at promoting circadian alignment and supporting stable well-entrained sleep-wake patterns) are predominantly implemented in athletes to improve performance, recovery and adaptation to travel. Emerging evidence from the broader population demonstrates that improving sleep and circadian health can also improve mental health, mood and well-being.
OBJECTIVES: To evaluate the current evidence on the effectiveness of sleep and circadian interventions for improving mental health, mood and well-being in athlete populations.
METHODS: Seven databases (CENTRAL, CINAHL, Embase, MEDLINE, PsycINFO, Scopus, SPORTDiscus) were searched from inception to 23 September, 2024 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Eligible studies involved athletes (participating in sport at any level) and evaluated sleep or circadian interventions aimed at improving sleep and/or circadian health, with mental health, mood or well-being outcomes. Sleep interventions directly manipulated sleep through behavioural, environmental or educational approaches. Studies without a comparator/baseline, using indirect methods (e.g. brainwave entrainment) to improve sleep or solely sleep restriction, were excluded. Two reviewers independently screened studies, extracted data, and assessed methodological quality and risk of bias using the Cochrane risk-of-bias tool and Joanna Briggs Institute checklist. Data were synthesised using a multi-level random-effects meta-analysis and pre-specified meta-regression.
RESULTS: A total of 21 sleep and circadian interventions have been implemented in sporting environments to improve the mental health of athletes. The interventions that have been investigated are constrained by limited sample sizes, a lack of female representation, a low-quality study design and inconsistent measurement of mental health, making it difficult to draw definitive conclusions of the efficacy of these strategies. The results of the meta-analysis showed that sleep and circadian interventions had a more substantial impact on positive affect compared to negative (β = 0.68, p < 0.001). The interventions were also found to be more effective in improving anxiety, tension and vigour compared to other subjective mood states. The limited interventions with a circadian component (e.g. light exposure) consistently found improvements in outcomes.
CONCLUSIONS: Sleep and circadian interventions appear to have the strongest effects on positive affect, anxiety, tension and vigour in athletes. Future research should address the limitations of existing studies by focusing on diverse and representative samples, incorporating a longer term follow-up after interventions, using consistent mental health measurements and developing interventions specifically aimed at improving athletes' circadian rhythms.
CLINICAL TRIAL REGISTRATION: The protocol was registered in the PROSPERO database (#CRD42023467548).
