Working throughout the night: beyond 'sleepiness'--impairments to critical decision making.

By the end of the first night on a 12h night-shift, wakefulness may have lasted up to 24h since the previous sleep. Although most work situations requiring critical decisions are foreseen and effectively resolved by well trained staff, such wakefulness can produce impairments in dealing with unexpected challenging situations involving uncertainty, change, distractions and capacity to evaluate risks. Also compromised can be the ability to engage in and keep abreast of protracted negotiations undertaken throughout the night. These effects, which are not just 'sleepiness', seem due to deteriorations with 'supervisory executive functions' of the prefrontal cortex; a region that appears particularly vulnerable to prolonged wakefulness. Recent research findings are presented to support this case, and some evidence-based recommendations made about practical countermeasures.