A recent study has found that young drivers who typically got six hours of sleep or less each night are more likely to get into a car accident.

A study by Alexandra L. C. Martiniuk, M.Sc, Ph.D., of The George Institute for Global Health, Sydney, Australia, and colleagues suggests less sleep per night is associated with a significant increase in the risk for motor vehicle crashes for young drivers.
Questionnaire responses were analyzed from 19,327 newly licensed drivers from 17 to 24 years old who held a first-stage provisional license between June 2003 and December 2004. Researchers also analyzed licensing and police-reported crash data, with an average of 2 years of follow up.
On average, individuals who reported sleeping 6 or fewer hours per night had an increased risk for crash compared with those who reported sleeping more than 6 hours.
Less weekend sleep was significantly associated with an increased risk for run-off-road crashes.