These episodes of drowsiness , whose duration can vary between a few minutes and a few hours, usually occur when our level of alertness declines . This is essentially what happens during so-called nap time.
However, if napping occurs at times when activity and attention levels should be higher, such as two hours after getting out of bed, they are usually indicative of some disorder. In this case, the phenomenon may be related to a sleep disturbance , as occurs in narcolepsy , which causes the desire to sleep during the day, and chronic drowsiness , micro-dreams, which cause 24% of fatal motorway accidents.
