Napping and cognitive performance during night shifts: a systematic review and meta-analysis

International audienceSTUDY OBJECTIVES: To examine the benefits of napping during night shifts on cognitiveperformance.METHODS: Medline, Cochrane Library, Science direct and Embase databases were searchedup to 01/07/2019. Cognitive performance during night shifts, both before and followingnapping or under control conditions (no nap), in working-aged adults, were analysed by timeand by type of cognitive function (executive function, attention, instrumental function andmemory). Estimates were pooled using random-effects meta-analysis.RESULTS: 18 articles (6 in real-work and 12 in laboratory) with a total of 494 participantswere included. The mean nap duration was 41.6±28.3 min, occurring between 12.00 and 4.10am, with a mean time set at 2.12 am. Cognitive performance did not differ at baseline betweenthe groups (effect size 0.02, 95%CI -0.09 to 0.13). There was an overall improvement inperformance following a nap compared to the control condition without a nap (0.25, 0.10 to0.41). Positioning naps early in the night and activity (simulated work tasks) tended to improvecognitive performance (-0.57, -1.16 to 0.002, and 0.082, -0.04 to 0.33, respectively). Theimprovements were primarily seen 30 minutes after awakening. Only memory deterioratedimmediately after awakening without an overall change in global cognitive performance.CONCLUSION: Napping during night shifts seems to improve cognitive performance.Napping early in the night and activity may benefit cognitive performance over time.Considering lack of data in real work environments, further studies are warranted beforepreconizing napping during night shifts as a preventive strategy (safety, health, economicoutcomes)