Sleep deprivation impairs lower-level cognition such as vigilant attention. However, the effect of sleep deprivation on higher-order cognition, such as problem solving or working memory, is not well understood. One prominent theory, referred to as the attention-mediated theory, posits that deficits in higher-order cognition can be entirely attributable to deficits in vigilant attention, as attention is a global process required for nearly all cognitive tasks. Across four of the largest sleep deprivation studies ever conducted, we investigated the effect of sleep deprivation on vigilant attention and a broadly relevant component of higher-order cognition called placekeeping. Placekeeping is important for problem solving and linear thinking, even more so than working memory capacity. In the evening, participants completed UNRAVEL, a measure of placekeeping ability and memory maintenance, and the Psychomotor Vigilance Task (PVT), a standard measure of vigilant attention, as a baseline assessment of performance. Participants were then randomly assigned to sleep at home for the night or to remain awake in the laboratory overnight. In the morning, all participants completed UNRAVEL and PVT again. In Experiment 1, we show that vigilant attention cannot fully account for deficits in placekeeping or memory maintenance after sleep deprivation. In Experiment 2, we show that the ability to manage proactive interference, a potentially important process of memory maintenance, did not show a significant deficit due to sleep deprivation. Experiments 3 and 4 investigate two interventions, caffeine and brief naps, and the extent to which they mitigate cognitive deficits due to sleep deprivation. Caffeine selectively benefitted vigilant attention but had no effect on placekeeping for the majority of participants. A brief nap during a period of sleep deprivation did not enhance vigilant attention or placekeeping performance; however, different aspects of sleep architecture during the naps were related to performance on the two tasks. Collectively, findings across the four studies do not support the attention-mediated theory; vigilant attention does not completely underlie deficits in placekeeping or memory maintenance after sleep deprivation. Instead, sleep deprivation appears to directly impair placekeeping and memory maintenance and may cause domain-specific deficits to cognition.
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