It seems I've been having more sleepless nights than normal . . . that's why caffeine was invented. But how long can you get away with substituting "coffee" for "sleep" and get away with it? A new study found that caffeine will keep you awake and alert after two straight nights where you sleep for five hours or less. But if you have three bad nights of sleep in a row or more, unfortunately no amount of caffeine will make you alert.
Read more at Daily Mail.