Sleep deprivation is a known risk factor for car crashes. In fact, researchers estimate that drowsy driving is responsible for 20 percent of all car crashes in the United States. But, up until now, studies have not focused on young drivers. Researchers point out that young people should be a target of education efforts to eliminate drowsy driving because their alertness, mood and physical performance are more adversely affected by sleep deprivation than older, more experienced drivers with similar sleep deprivation.

Sleep deprivation contributes to car crashes because it impairs elements of human performance that are critical to safe driving. Sleepiness reduces optimum reaction times, causes delayed responding in attention-based tasks, and increases the time it takes to process and integrate information. Even moderately sleepy drivers can have a performance-impairing increase in reaction time that will prohibit stopping in time to avoid a collision.

The new study involved more than 19,000 young, newly-licensed drivers living in New South Wales, Australia, who fielded questions about their sleep habits, including weeknights and weekends. Then researchers tracked the participants, aged 17-24, for two years, and obtained police reports to document car accidents.

The drivers who reported sleeping six or fewer hours per night were about 20 percent more likely to be involved in a car crash, compared with those who got more than six hours of sleep a night. Among the sleep-deprived, car crashes were most likely to occur between 8 p.m. and 6 a.m.

Even after researchers considered other factors that affect people’s risk of a crash, such as age, number of driving hours per week, risky driving behavior such as speeding and a history of car accidents, the same findings held.

The researchers did note however, that participants were only asked about their sleep habits once over the course of the study, so the exact number of hours participants slept the day before they were involved in a crash is unknown.

Still, researchers hope the new findings will increase understanding of the impact of reduced hours of sleep on crash risk, and pinpoint subgroups of young drivers to facilitate education.


Most of us will automatically set our clocks ahead one hour in observance of Daylight Saving Time (DST) and besides feeling a little sleepy the next morning, we won’t give it a second thought. However, adjusting your clock on Saturday night or Sunday morning could leave you with a 40-60 minute sleep deficit by Monday morning, and it’s this seemingly insignificant loss of sleep that can cause problems.

Research shows on Monday and Tuesday after the time change, our risk of having a car accident increases by about 6%. Groggy people waking and driving to work in the dark are more prone to accidents. Our chance of being in a workplace accident increases, too, as does the severity of those accidents. In the days following the shift to DST, workplace productivity traditionally plummets as well with a documented increase in “cyber-loafing.”

DST was enacted during World War I to decrease energy use. Benjamin Franklin first advocated for the practice in 1784 because he noticed people using candles at night and sleeping past dawn in the morning. By shifting time by an hour during the summer, they would burn fewer candles and not sleep through the morning sunlight.

However, some observers see nothing but downsides in their data to setting the clocks ahead, even going so far as to dub the Monday after the time change “Sleepy Monday” or “Risky Monday.” Tuesday and Wednesday are more dangerous than usual, as well. However, the risks begin to decrease as the week progresses.

Also, the time change does not save on energy either. By facilitating more outdoor time, it actually prompts us to spend more money at amusement parks and local sporting events, and spending longer evenings out sends us to the ATM and the gas pump more often.

The impacts of DST are likely related to our body’s internal circadian rhythm, our internal “clocks.” The problems with DST are worst in the spring, when we’ve all just lost one hour of sleep. The sun rises later, making it more difficult to wake in the morning. This is because we reset our body clocks using the light. When these clues change abruptly, it causes confusion. To help offset this confusion, try going to bed an hour earlier when you set your clock ahead.