Demands of modern society force many work operations into the night when the internal circadian timekeeping system is promoting sleep. The combination of disturbed daytime sleep and circadian misalignment, which is common in overnight shift work, decreases cognitive performance, yet how performance may differ across multiple consecutive nights of shift work is not fully understood. Therefore, the primary aim of this study was to use a simulated night-shift protocol to examine the cognitive performance and ratings of sleepiness and clear-headedness across the hours of a typical daytime shift, a first night shift with an afternoon nap and extended wakefulness, and 2 subsequent overnight shifts. We tested the hypothesis that cognitive performance would be worse on the first night shift as compared with the baseline and subsequent nighttime shifts and that performance during nighttime shifts would be reduced as compared with the baseline daytime shift. Fifteen healthy adults (6 men) were studied in the 6-day in-laboratory protocol. Results showed that working during the night increased subjective sleepiness and decreased clear-headedness and performance on the Psychomotor Vigilance Task (i.e., slower median, fastest and slowest reaction times, and increased attentional lapses), Stroop color word task (decreased number of correct responses and slower median reaction time), and calculation addition performance task (decreased number attempted and correct). Furthermore, we observed limited evidence of sleepiness, clear-headedness, or performance adaptation across subsequent nights of simulated night work. Our findings demonstrate that night-shift work, regardless of whether it is the first night shift with a nap and extended wakefulness or subsequent night shifts, decreases performance and clear-headedness as compared with the day shift.

中文翻译：

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过渡到夜间工作和随后的夜班期间的认知障碍。


现代社会的需求迫使许多工作在夜间进行，此时内部昼夜节律计时系统正在促进睡眠。白天睡眠受到干扰和昼夜节律失调（这在夜班工作中很常见）会降低认知能力，但连续多个晚上的轮班工作中认知能力有何不同尚不完全清楚。因此，本研究的主要目的是使用模拟夜班方案来检查典型日班、第一个夜班、下午小睡和长时间清醒的认知表现以及困倦和头脑清醒的评级，以及随后的 2 个夜班。我们测试了这样的假设：与基线和随后的夜班相比，第一个夜班的认知表现会更差，并且与基线日班相比，夜班期间的表现会下降。在为期 6 天的实验室方案中对 15 名健康成年人（6 名男性）进行了研究。结果表明，夜间工作会增加主观睡意，并降低头脑清醒和精神运动警戒任务（即中位数较慢、最快和最慢的反应时间，以及注意力不集中增加）和斯特鲁普颜色词任务（正确反应数量减少）的表现。和较慢的中位反应时间），以及计算附加性能任务（尝试和正确的次数减少）。此外，我们在随后的模拟夜间工作中观察到了有限的困倦、头脑清醒或表现适应的证据。 我们的研究结果表明，与白班相比，夜班工作无论是第一个小睡并长时间保持清醒的夜班还是随后的夜班，都会降低工作表现和头脑清醒。