Short sleepers -- even when they feel well-rested -- are more likely to be drowsy drivers than people who get more shuteye each night, according to a new study.


Researchers from the University of Pennsylvania's Perelman School of Medicine found that people who sleep an average of fewer than six hours each night are three times more likely to report having driven while drowsy in the last month, compared with people who get seven hours a night.


Plus, people who sleep five or fewer hours a night, on average, are four times as likely to report drowsy driving in the last month, compared with those getting seven hours.


"Falling asleep at the wheel[1] is a major cause of road accidents. It might even be more of a problem than drunk driving, since it is responsible for more serious crashes per year," study researcher Michael Grandner, Ph.D., a psychiatry instructor and member of the Center for Sleep and Circadian Neurobiology at the university, said in a statement. "We already know that people who are sleep-deprived in the laboratory have impaired driving performance, but we haven't been able to better define what sleep profiles and patterns put drivers in the general population at the highest risk."


Indeed, a recent study in the Archives of Internal Medicine did show that the risk of car accidents[2] is the same with drunk driving and drowsy driving -- both double car accident risk.


The new study, which is published in the journal Accident Analysis and Prevention[3] , is based on data from the Center for Disease Control and Prevention's 2009 Behavioral Risk Factor Surveillance System, which had information from 31,522 people.


Even though it may not be surprising that people who get less sleep are more likely to report drowsy driving, what is notable is that researchers found that short sleepers who report getting enough sleep each night are still at a three times higher risk for driving drowsy.



While the amount of sleep each person requires is different[4] , with some needing more than others, the National Sleep Foundation notes that adults should generally get somewhere between seven and nine hours a night.


Just this year, a CDC study showed that one in 24 adults in the U.S. has reported falling asleep while at the wheel[5] , with officials worried that the number could actually be even higher since nodding off while driving can happen so quickly.



Also on HuffPost:




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  • ...Increase Stroke Risk


    Even without the typical risk factors, like being overweight or having a family history, short sleep can up your risk for stroke, according to 2012 research. Adults who regularly slept fewer than six hours a night had <a href="http://www.huffingtonpost.com/2012/06/11/sleep-stroke-risk_n_1586837.html">four times the risk of stroke symptoms</a>, HuffPost reported.




  • ...Lead To Obesity


    Too little sleep can spur some less-than-ideal food choices, including <a href="http://www.huffingtonpost.com/2013/02/25/sleep-portion-sizes-deprivation-food-calories_n_2735497.html">serving yourself larger portions</a>, and a hankering for junk food, thanks to some complicated hormonal changes that occur when you don't get sufficient shuteye. It seems that six hours of sleep or less <a href="http://www.huffingtonpost.com/2012/10/26/sleep-deprivation-obesity-leptin-ghrelin-insulin_n_2007043.html">bumps up production of the hunger hormone ghrelin</a> and limits leptin, which helps you balance your food intake, according to a 2012 review of 18 studies of sleep and appetite.




  • ...Up Diabetes Risk


    A pair of small studies from 2012 examined the link between poor sleep and insulin resistance, a telltale risk factor for diabetes. One found that among healthy teenagers, the <a href="http://www.huffingtonpost.com/2012/10/03/sleep-insulin-resistance-teens_n_1929374.html">shortest sleepers had the highest insulin resistance</a>, meaning the body is <a href="http://diabetes.niddk.nih.gov/dm/pubs/insulinresistance/#resistance">not using insulin effectively</a>, according to the National Institute of Diabetes and Digestive and Kidney Diseases. The second study examined fat cells, in particular, and found that cutting back on sleep <a href="http://annals.org/article.aspx?articleid=1379773">increased insulin resistance in these cells</a>, even when <a href="http://news.health.com/2012/10/15/sleep-deprivation-insulin-resistance/">diet and calorie intake were restricted</a>, Health.com reported.




  • ...Fuel Memory Loss


    You probably know that on the days when you are most tired, you're forgetful and unfocused -- but sleep deprivation can lead to <a href="http://www.sciencedaily.com/releases/2013/01/130127134212.htm"><em>permanent</em> cognitive issues</a>. The less we sleep, the less we benefit from the memory-storing properties of sleep. But additionally, a lack of sleep can cause <a href="http://www.huffingtonpost.com/2013/01/28/sleep-deprivation-memory-loss_n_2566999.html">"brain deterioration,"</a> according to a 2013 study, which may at least in part explain memory loss in seniors.




  • ...Damage Bones


    At least in rats, long-term <a href="http://ebm.rsmjournals.com/content/237/9/1101.full">sleep deprivation seems to contribute to osteoporosis</a>, according to a 2012 study. Researchers found <a href="http://www.huffingtonpost.com/2012/09/26/sleep-deprivation-bones-marrow_n_1898610.html">changes to bone mineral density and bone marrow</a> in the rodents when they were deprived of shuteye over a period of 72 days. "If true in humans, and I expect that it may be, this work will have great impact on our understanding of <a href="http://www.eurekalert.org/pub_releases/2012-09/sfeb-los_1091812.php">the impact of sleep deprivation on osteoporosis</a> and inability to repair bone damage as we age," Steven R. Goodman, Ph.D., editor-in-chief of Experimental Biology and Medicine, said in a statement.




  • ...Increase Cancer Risk


    A small (but growing) body of research suggests that short and poor sleep can up risk for certain types of cancer. A 2010 study found that among 1,240 people screened for colorectal cancer, the 338 who were diagnosed were <a href="http://onlinelibrary.wiley.com/doi/10.1002/cncr.25507/abstract">more likely to average fewer than six hours of sleep</a> a night. Even after controlling for more traditional risk factors, polyps were more common in people who slept less, according to the study. Getting just six hours of sleep a night has also been linked to an <a href="http://www.huffingtonpost.com/2012/09/06/sleep-breast-cancer-aggressive-deprivation_n_1854658.html">increase of recurrence in breast cancer patients</a>. The study's author has pointed to more and better sleep as a possible pathway of reducing risk and recurrence.




  • ...Hurt Your Heart


    The stress and strain of too little sleep can cause the body to produce more of the chemicals and hormones that can lead to heart disease, according to 2011 research. The study found that people who slept for six hours or less each night and have problems staying asleep had a 48 percent <a href="http://www.sciencedaily.com/releases/2011/02/110208091426.htm">higher risk of developing or dying from heart disease</a>.




  • ...Kill You


    It's not just heart problems that can lead to sleep-deprivation-related death. In fact, <a href="http://healthland.time.com/2010/09/02/lack-of-sleep-can-cause-depression-weight-gain-and-even-death/">short sleepers seem to die younger</a> of any cause than people who sleep about 6.5 to 7.5 hours a night, TIME reported. A 2010 study examined the impact of short sleep on mortality and found that <a href="http://www.journalsleep.org/ViewAbstract.aspx?pid=27894">men who slept for less than six hours of sleep a night were four times more likely</a> to die over a 14-year period. The study's authors called this link "a risk that has been underestimated."




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