Sleep deprivation and impaired cognition. Possible role of brain catecholamines

To assess the role of brain catecholamines in cognitive decline associated with sleep deprivation, 40 healthy male volunteers were randomized to conditions of total sleep deprivation or 40.5 h of rest. Within each sleep condition, subjects were further randomized to treatment with a 2-day regimen of placebo or alpha-methyl-para-tyrosine (AMPT), a catecholamine synthesis inhibitor. Cognitive performance was measured repeatedly over time using a computerized performance assessment battery. Treatment with AMPT or treatment with sleep deprivation increased sleepiness without producing marked or consistent deterioration in performance. By contrast, subjects who received both treatments reported greater sleepiness than those receiving either treatment alone, and developed severe cognitive impairment on a variety of tasks. These findings, along with previous evidence that catecholamine-enhancing drugs improve performance in sleep-deprived individuals, support the view that decline in cognitive performance during sleep deprivation may be mediated by brain catecholamines.