STUDY OBJECTIVES To examine the benefits of napping during night shifts on cognitive performance. METHODS Medline, Cochrane Library, Science direct and Embase databases were searched up to 01/07/2019. Cognitive performance during night shifts, both before and following napping or under control conditions (no nap), in working-aged adults, were analysed by time and by type of cognitive function (executive function, attention, instrumental function and memory). Estimates were pooled using random-effects meta-analysis. RESULTS 18 articles (6 in real-work and 12 in laboratory) with a total of 494 participants were included. The mean nap duration was 41.6±28.3 min, occurring between 12.00 and 4.10 am, with a mean time set at 2.12 am. Cognitive performance did not differ at baseline between the groups (effect size 0.02, 95%CI -0.09 to 0.13). There was an overall improvement in performance following a nap compared to the control condition without a nap (0.25, 0.10 to 0.41). Positioning naps early in the night and activity (simulated work tasks) tended to improve cognitive performance (-0.57, -1.16 to 0.002, and 0.082, -0.04 to 0.33, respectively). The improvements were primarily seen 30 minutes after awakening. Only memory deteriorated immediately 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 before preconizing napping during night shifts as a preventive strategy (safety, health, economic outcomes).

中文翻译：

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夜班小睡和认知表现：系统评价和荟萃分析

研究目标 研究夜班小睡对认知能力的益处。方法 Medline、Cochrane 图书馆、Science direct 和 Embase 数据库的检索时间截至 2019 年 1 月 7 日。通过时间和认知功能类型（执行功能、注意力、工具功能和记忆）分析工作年龄成年人在小睡前后或在控制条件（不小睡）下夜班期间的认知表现。使用随机效应荟萃分析汇总估计值。结果 18 篇文章（6 篇在实际工作中，12 篇在实验室中），共有 494 名参与者被纳入。平均午睡时间为 41.6±28.3 分钟，发生在凌晨 12 点至 4.10 点之间，平均时间设置为凌晨 2.12 点。两组之间的基线认知表现没有差异（效果大小为 0.02，95% CI -0.09 至 0.13）。与没有午睡的对照条件相比，午睡后的表现有整体改善（0.25、0.10 至 0.41）。在夜间和活动（模拟工作任务）中早点小睡往往会提高认知能力（分别为 -0.57、-1.16 至 0.002 和 0.082、-0.04 至 0.33）。改善主要出现在醒来后 30 分钟。醒来后只有记忆力立即恶化，而整体认知表现没有整体变化。结论 夜班小睡似乎可以提高认知能力。随着时间的推移，早睡和活动可能有益于认知能力。考虑到缺乏实际工作环境中的数据，在将夜班小睡作为预防策略（安全、健康、经济成果）之前，有必要进行进一步的研究。