Scientists have found that a small nightly decrease in sleep has serious cumulative effects; for instance, a week and a half spent sleeping just six hours per night, rather than seven to nine, can result in the same level of impairment on the tenth day as being awake for the previous 24 hours straight.
Recent studies have shown that staying awake for just 17 to 19 hours straight impacts performance more than a blood-alcohol level of .05 percent (the level considered legally drunk in most western European countries). This level of impairment slows an individual’s reaction time by about 50 percent compared to someone who is well rested. Twenty-four hours of continuous wakefulness induces impairments in performance equivalent to those induced by a blood-alcohol level of 0.10 percent, beyond the legal limit for alcohol intoxication in many areas.
Perhaps even more profound is the effect of poor sleep on judgment. The prefrontal cortex, an area near the front of the brain responsible for logical reasoning and complex thought, seems particularly vulnerable to sleep deprivation. Experts think this may explain why people typically have such a hard time recognizing their own fatigue and level of impairment.
