According to a survey made by the TNS Sofres (a French survey enterprise) in 2006 for the Institute for Sleep and Vigilance, "27% of the French people are disturbed by a problem of sleepiness.
One adult in ten, one teenager in five has a chronic sleep lack."
The first cause of excessive daytime sleepiness (EDS) is often the least investigated in accidentology studies : it is the chronic lack of sleep.
The subject, who has though a good quality of sleep, cannot adapt to the social, familial and professional demands which are imposed on him/her.
Here, it is truly a matter of a chronicadaptation disorder because an occasional lack of sleep is easily compensated thanks to the power of rebound sleep the following night or during a nap. Here, the subject suffers all the time from a need to sleep which he/she often fights with a constant behavioural agitation.
All studies show that sleep deprivation leads to a fall of intellectual, emotional and physical performances.
The endocannabinoid system (cf.) allows to understand better the consequences of sleep deprivation on appetite, immunity, pain and mood.
The first consequence of sleep lack is the risk of accidents linked to excessive sleepiness.
It has been measured that the average duration of sleep has fallen of more than one hour in the last century. Our grandparents have grown up in a world where people went to sleep much earlier than now.
Average sleep duration has thus gone from 9 to 7 hours a day.
More and more individuals take on their sleep time because the choice of activities which can be made at night becomes larger all the time.
Television, video games, Internet and work at home are the main reasons to delay bedtime.
It appears clearly that children and teenagers are amongst the population which is most exposed to a lack of sleep.
Studies agree to demonstrate the very negative impact of sleep deprivation on memory and, as it was discovered more recently, on social behaviour or food intake balance.
A perfect control of one’s sleep seems to be one of modern life’s challenges...
The other causes of sleep deprivation mostly concern night and shift workers who do not have the ability to compensate their sleep debts by a good quality diurnal sleep. It is particularly the case of the « morning subjects » who are more vulnerable regarding night work.
On the opposite, « evening subjects » are hindered by the actual work schedules and stand very badly, for example, the advice to go to work early from « Bison futé » (a French traffic radio station).
With night workers, the rest conditions (noise, temperature, lighting, environment quality) must be taken into account to estimate and prevent the risk of excessive daytime sleepiness.
Special chromotherapy glasses (which limit the arousing effect of the morning light), enhance night workers’ diurnal sleep.
The subject would benefit of a satisfying sleep if he/she only could dissociate his sleep/wake rhythm from the social rhythms. He/she suffers from difficulties to sleep at the « right moment ».
Sleep typology studies highlight the « extreme evening » characteristics of these sleepers (who are often rather long sleepers).
The interview of (voluntary) night workers puts forward similar characteristics with a good adaptation to diurnal sleep.
"FAPS" is a dominant autosomic disturbance of the circadian rhythm. The concerned subjects are "very early risers" with a phase advance of 4 hours of sleep rhythm, body temperature, and melatonin secretion. (...) Some circadian rhythm disturbances can thus be imputed to a genetic mutation (affecting gene hPer2, very close to that known in Drosophila)."
A behavioural phase advance (too early bedtime because of boredom +++) can be encountered in the interview of subjects who suffer from maintaining sleep insomnia.
Too many old subjects are thus treated erroneously for insomnia because they are awake from the middle of the night.
A good sleeper goes to sleep trustfully, wakes up fit... and must not be sleepy during the day.
 The BAAC file, bulletin of analysis of traffic accidents with body injuries, does not mention the notion of sleepiness before or during the accident