Sleep-deprived people perform below par at work. Some workers fall asleep at their desk, while listening to a lecture or in meetings, driving on a monotonous road, operating hazardous machinery, monitoring industrial plants and providing medical surveillance. Even if they do not fall asleep, their ability to attend to crucial details and their judgement are likely to be seriously impaired.
43% of US adults admit that they are so sleepy during the day that it interferes with their daily activities for a few days or more a month. One out of five adults (20%) experience this level of daytime sleepiness at least a few days a week or more. Nearly one in ten adults admit to having to change their jobs in order to get more sleep.
One-third of the one million truck drivers on highways in the USA may be too tired to stay awake while driving or to respond quickly enough to avert an accident. Sleepiness is believed to be responsible for a large share of long-haul vehicle accidents. Undue fatigue has resulted in pilots' failing to read gauges correctly and landing not only on the wrong runway but even at the wrong airport. Many major industrial accidents occurred at night when it is probable that workers were not optimally alert.
A survey of 200,000 workers in 10,000 private companies in Japan in 1982 showed that 72.8% of male workers complained of mental fatigue and 64.7% of physical fatigue caused by their job. The corresponding figures for female workers were 65.5% and 64.5%.