Human cognitive impairment associated with sleep loss, circadian misalignment and work overload is a major concern in any high stress occupation but has potentially catastrophic consequences during spaceflight human robotic interactions. Two safe, wake-promoting countermeasures, caffeine and blue-enriched white light have been studied on Earth and are available on the International Space Station. We therefore conducted a randomized, placebo-controlled, cross-over trial examining the impact of regularly timed low-dose caffeine (0.3 mg per kg per h) and moderate illuminance blue-enriched white light (~90 lux, ~88 melEDI lux, 6300 K) as countermeasures, separately and combined, in a multi-night simulation of sleep-wake shifts experienced during spaceflight among 16 participants (7 F, ages 26–55). We find that chronic administration of low-dose caffeine improves subjective and objective correlates of alertness and performance during an overnight work schedule involving chronic sleep loss and circadian misalignment, although we also find that caffeine disrupts subsequent sleep. We further find that 90 lux of blue-enriched light moderately reduces electroencephalogram (EEG) power in the theta and delta regions, which are associated with sleepiness. These findings support the use of low-dose caffeine and potentially blue-enriched white light to enhance alertness and performance among astronauts and shiftworking populations.

与睡眠不足、昼夜节律失调和工作超负荷相关的人类认知障碍是任何高压力职业中的一个主要问题，但在航天人类机器人交互过程中可能会产生灾难性后果。咖啡因和富蓝光白光这两种安全的促醒对策已在地球上进行了研究，并可在国际空间站上使用。因此，我们进行了一项随机、安慰剂对照、交叉试验，检查定期低剂量咖啡因（0.3mg/kg/h）和中等照度的富蓝光白光（~90 lux、~88 melEDI lux、 6300 K）作为对策，分别和组合，在 16 名参与者（7 F，年龄 26-55）在太空飞行期间经历的睡眠-觉醒转变的多晚模拟中。我们发现，长期服用低剂量咖啡因可以改善涉及慢性睡眠不足和昼夜节律失调的夜间工作计划中警觉性和表现的主观和客观相关性，尽管我们也发现咖啡因会扰乱随后的睡眠。我们进一步发现，90 勒克斯的蓝光增强光会适度降低与困倦相关的 θ 区和 δ 区的脑电图 (EEG) 功率。这些发现支持使用低剂量咖啡因和可能富含蓝色的白光来提高宇航员和轮班工作人群的警觉性和表现。