Because all humans require sleep on a daily basis, anyone can succumb to drowsy driving, loss of alertness and microsleep (National). There are many underlying causes for this condition, including sleep loss from restriction, interruption or fragmentation of sleep, chronic sleep debt, circadian factors associated with driving patterns or work schedules, time on the job, the use of sedative medications, and the consumption of alcohol. These factors are all cumulative, and a combination of more than one increases the risk of a traffic accident. It is impossible to give the top ten causes because the cause varies from one person to another, and there may be multiple causes within the one person, e.g. lack of sleep and alcohol consumption. There are no statistics on the percentages of each cause in relation to fatigue while driving. There are no guidelines along which a person can tell when they have been driving too long. If you feel fatigues while driving, you should take a rest (Foundation; National; NYS).
Car crashes tend to occur at times in keeping with people's circadian rhythms when sleepiness is most pronounced, during the night and the mid-afternoon (National). Lifestyle factors also make people drowsy while driving, and so do sleep disorders. Research has shown that young males, shift workers, commercial drivers, and people with untreated sleep disorders or with short-term or chronic sleep deprivation are at an increased risk for having a sleep-related traffic accident (National; NYS). Specific at-risk groups are males under age 26; shift workers, who have a 6 times greater risk, and those on rotating shifts or working more than 60 hours a week who have a 40 percent higher risk of being in an accident; at least 15 percent of heavy truck accidents are due to fatigue; people with undiagnosed sleep disorders and obstructive sleep apnea are seven times more likely to have a sleep-related traffic accident; business tra...