Which individually-directed non‐pharmacological interventions are effective at improving sleep outcomes in shift workers? A systematic review of systematic reviews

Shift work can result in sleepiness, increasing risks of accidents, absenteeism and illness. Systematic reviews have examined individually-directed non-pharmacological interventions (e.g., light therapy, napping) for shift workers, but the diversity of interventions, settings and review conclusions make it difficult to determine which interventions work. We conducted a systematic review of systematic reviews to appraise evidence for such interventions to improve sleep or reduce sleepiness in shift workers. Six databases were searched and screened with good reliability. Two reviewers independently extracted data from all identified reviews, and a narrative synthesis was conducted. Twenty-eight systematic reviews were included, containing 69 primary studies involving 4947 participants. Twenty-three reviews were critically low-quality. The most-investigated interventions were light therapy (n = 8 reviews) and napping (n = 7 reviews). High-quality reviews suggested inconclusive evidence for which interventions improved sleep quality, sleep quantity and subjective sleepiness in shift workers, although lower quality reviews indicated light therapy, napping, physical activity, dietary supplements, mobile health apps and mindfulness may be effective. We have identified several promising interventions to improve sleep or reduce sleepiness in shift workers, although none met high-quality thresholds. More rigorous and high-quality trials should focus on these promising interventions.