WE investigated the effect of sleep deprivation on postural control during a simple reaction time task (SRT), during a task requiring the intermittent inhibition of a reaction (IRT), and in the absence of a concurrent information processing task. Postural sway, i.e. changes in center of pressure on a force platform, was recorded in three increasingly difficult standing conditions (fixed platform, sway-referenced platform and sway-referenced platform with sway-referenced visual scene) during the three information-processing task conditions. Five healthy subjects performed the tasks either after normal sleep or following 24 h of sustained wakefulness. As hypothesized, sleep deprivation significantly increased postural sway only in the IRT condition. Within the IRT condition, sleep deprivation significantly increased sway across all postural conditions.