The impact of psychostimulants on sustained attention over a 24-h period.

The off-label use of psychostimulants is a growing trend in healthy adults with many turning to these medications to increase alertness, attentional focus, and to help them study. However, the empirical literature on the efficacy of these medications for cognitive enhancement is controversial and the longer-term impact of these drugs on health and cognitive processing has not been thoroughly examined. Specifically, sleep supports daytime alertness, vigilance, and sustained attention, yet stimulants significantly disrupt sleep. Here, using a double-blind, placebo-controlled, crossover design, we tested the impact morning administration of psychostimulants (dextroamphetamine; DEX) had on: (1) tests of attention 75-min and 12-h after drug ingestion, (2) nighttime sleep and (3) post-sleep attention in healthy, young adults. First, we found that repeated testing led to significant decreases in performance from baseline in the placebo condition, and that DEX, compared to placebo, prevented deterioration at the 75-min test, and selectively for visual field at the 12 h and 24 h tests. We also found that stimulants, compared to placebo, benefitted attentional processing 75-min post-drug but this did not persist to the delayed test 12-h after drug administration. Additionally, morning stimulant administration resulted in robust nighttime sleep disruptions, yet post-sleep sustained attention was equivalent in the stimulant and placebo conditions, indicating that the initial boost to performance dissipated at 24 h, but the decrease was not significantly worse than placebo. Together, these results suggest that stimulant medications, commonly used off-label for cognitive enhancement may prevent deterioration of sustained attention brought on by repeated within-day testing. Additionally, these medications substantially disrupt nighttime sleep; which while coming at little cost to next-day attentional processing, may have steeper consequences for other cognitive domains.