Behavioral Biology Branch, Center for Military Psychiatry and Neuroscience Research, Walter Reed Army Institute of Research.
Sleep. 2017 Dec 1;40(12). doi: 10.1093/sleep/zsx171.
To investigate the effects of caffeine on psychomotor vigilance and sleepiness during sleep restriction and following subsequent recovery sleep.
Participants were N = 48 healthy good sleepers. All participants underwent five nights of sleep satiation (time-in-bed [TIB]: 10 hours), followed by five nights of sleep restriction (TIB: 5 hours), and three nights of recovery sleep (TIB: 8 hours) in a sleep laboratory. Caffeine (200 mg) or placebo was administered in the form of chewing gum at 08:00 am and 12:00 pm each day during the sleep restriction phase. Participants completed hourly 10-minute psychomotor vigilance tests and a modified Maintenance of Wakefulness Test approximately every 4 hours during the sleep restriction and recovery phases.
Caffeine maintained objective alertness compared to placebo across the first 3 days of sleep restriction, but this effect was no longer evident by the fourth day. A similar pattern of results was found for Maintenance of Wakefulness Test sleep latencies, such that those in the caffeine group (compared to placebo) did not show maintenance of wakefulness relative to baseline after the second night of restriction. Compared to placebo, participants in the caffeine condition displayed slower return to baseline in alertness and wakefulness across the recovery sleep period. Finally, the caffeine group showed greater N3 sleep duration during recovery.
Caffeine appears to have limited efficacy for maintaining alertness and wakefulness across 5 days of sleep restriction. Perhaps more importantly, there may be recovery costs associated with caffeine use following conditions of prolonged sleep loss.
研究咖啡因在睡眠限制期间和随后的恢复性睡眠期间对精神警觉和嗜睡的影响。
参与者共有 48 名健康的良好睡眠者。所有参与者均接受了五晚的睡眠饱和（卧床时间[TIB]：10 小时），随后进行了五晚的睡眠限制（TIB：5 小时），并在睡眠实验室中进行了三晚的恢复性睡眠（TIB：8 小时）。在睡眠限制阶段的每天上午 8 点和下午 12 点，以咀嚼胶的形式给予咖啡因（200mg）或安慰剂。在睡眠限制和恢复阶段，参与者每小时完成 10 分钟的精神警觉性测试和修改后的维持清醒测试，大约每 4 小时进行一次。
与安慰剂相比，咖啡因在睡眠限制的前 3 天内保持了客观的警觉性，但第四天就不再明显。维持清醒测试的睡眠时间也出现了类似的结果，即与限制后的第二天相比，咖啡因组（与安慰剂相比）在限制后没有保持清醒。与安慰剂相比，咖啡因组在恢复睡眠期间，警觉性和清醒度的恢复速度较慢。最后，咖啡因组在恢复期间显示出更长的 N3 睡眠时间。
咖啡因在 5 天的睡眠限制期间似乎对保持警觉和清醒的效果有限。也许更重要的是，在经历了长时间的睡眠剥夺后，使用咖啡因可能会带来恢复方面的代价。
