The following was just reported in the Harvard Business Review. The authors discussed the results in terms of how the workforce is hurting productivity, but it applies pretty generally. All of these findings can be explained easily with basic cognitive science as global fatigue of activation, particularly inhibitory connections. But we often don't account for them in design, either of products that people use when they are sleepy or work systems where employees may be sleepy.
• Stay awake longer than 18 consecutive hours and your reaction speed, memory, attention-span and decision-making all start to suffer.
• Five or six hours of sleep a night for several days in a row has a cumulative effect that magnifies these negatives.
• Throughout the waking day, humans build up a stronger and stronger drive for sleep.
• Most people can't get to sleep without some wind-down time, even if they are very tired.
• There is a transitional phase between when you wake up and the time your brain becomes fully functioning. This is why making key decisions at the crack of dawn is never a good idea.
• A person who is sleep deprived has no idea how functionally impaired he or she actually is.
Source: "Sleep Deficit: The Performance Killer," Harvard Business Review, October, 2006, Vol. 84, No. 10. Pages 53-59.
