The impact of a personalized sleep & nutrition intervention in shift workers: improved subjective sleep without objective changes.

Abstract

This study examined the effects of a personalized sleep or nutrition intervention on sleep in shift-workers. Fifty-seven healthy male workers on 12-hour shifts received the sleep intervention (n=25), nutrition intervention (n=22), or control (n=10). The sleep intervention aimed to improve sleep duration and quality through adjustments in sleep timing and sleep education. The nutrition intervention targeted circadian alignment by structuring meal timing and macronutrient distribution. Interventions were personalized using baseline sleep, diet, and physiological markers. Subjective sleep was assessed with the Insomnia Severity Index at baseline, last weeks of the intervention, and 8-month follow-up. Objective sleep outcomes (total sleep time, sleep efficiency, fragmentation index, and wake after sleep onset) were assessed through actigraphy at baseline, first and last weeks of the intervention. Mixed-effects models analyzed changes in subjective and objective sleep outcomes, adjusting for age, chronotype and household composition. The sleep intervention group had significantly higher insomnia scores at baseline, which improved to control levels post-intervention and remained so at follow-up. However, no significant changes in objective sleep were observed. The nutrition intervention group showed no significant effects on subjective or objective sleep outcomes. These findings suggest personalized sleep strategies may improve perceived sleep without detectable changes in objective measures.