Summary Previous research suggests that sleep deprivation is associated with declines in metabolic activity within brain regions important for judgement and impulse control, yet previous studies have reported inconsistent findings regarding
the effects of sleep loss and caffeine on risk‐taking. In this study, 25 healthy adults (21 men, four women) completed the Balloon Analog Risk Task (BART) and Evaluation of Risks (EVAR) scale at regular intervals to examine behavioral and self‐reported risk‐taking
propensity during 75 h of continuous sleep deprivation. Participants received either four double‐blind administrations of 200 mg caffeine (n =12) or indistinguishable placebo (n =13) gum bi‐hourly during each of the
3 nights of sleep deprivation. No significant effects of drug group or sleep deprivation were evident on the BART or EVAR when measured at 51 h of wakefulness. However, by 75 h, the placebo group showed a significant increase in risk‐taking behavior on the cost–benefit
ratio and total number of exploded balloons on the BART, whereas the caffeine group remained at baseline levels. On the EVAR, several factors of self‐reported risk‐taking propensity, including total risk, impulsivity and risk/thrill seeking, were reduced among subjects receiving
caffeine across the 3 days of sleep deprivation, but remained at baseline levels for the placebo group. These results suggest that 3 nights of total sleep deprivation led to a significant increase in behavioral risk‐taking but not self‐reported perception of risk‐propensity.
Overnight caffeine prevented this increase in risky behavior.