Had a bad night’s sleep? There is a good chance that you will be just a little less alert the next day. That ‘less alert’ turns out to be more drastic than you might think. Beter Bed reports that those who sleep less than four hours in a day have a fifteen times greater chance of causing a car accident. Anyone who does not sleep for 24 hours or who sleeps four to five hours a night for a week has the responsiveness and alertness behind the wheel of someone who has consumed four glasses of alcohol (1.0 promille). According to Beter Bed, no less than 21 percent of all fatal car accidents in which one or more people are killed are caused by drowsy drivers.