Is Your Coffee Betraying You?

The study followed 48 individuals whose sleep was restricted to five hours per night for five nights. Each following day, the individuals were either given a 200 mg caffeine pill or a placebo pill, followed by a series of tests.

Scores on tests measuring reaction time and mood were higher for the caffeinated group for the first two days, but NOT for the the days after that. 

By the third day of the study, overall ratings for happiness were lower for the people who had gotten the caffeine compared with those who had not. And by the end of the experiment, those in the caffeine group rated themselves as more annoyed than those who had not had caffeine.

The study was presented earlier this week at a meeting of sleep medicine physicians, researchers and professionals in Denver, Colorado. 

The good news is that reaping the alertness- and performance-boosting benefits of caffeinated coffee is still possible any day — as long as you haven’t gotten more than three poor nights of sleep in a row. 

Bottom line: If you haven’t slept well in a few days, a nap (and a good night’s shuteye!) is going to do you a lot more good than another cup of coffee.

Sarah DiGiulio is The Huffington Post’s sleep reporter. You can contact her at sarah.digiulio@huffingtonpost.com.