I basically run on coffee, so this is good news. A team of researchers in Scotland looked at how late in the day you can drink coffee, and not have to worry about all that caffeine keeping you up at night.
And the answer is...stop drinking stuff with caffeine 6 hours before bed. After that, it can mess with your internal clock. The study also found that drinking 4 to 5 cups a day is totally fine as long as you stop early enough. But some people metabolize caffeine more slowly, so keep that in mind.
In other coffee news: A big study in the U.K. just found that drinking 3 to 4 cups a day can lower your risk for liver cancer. It tracked a half-million people for more than a decade. And coffee drinkers were 49% less likely to die of chronic liver disease.