Coffee alone may do an okay job of waking you up during that mid-afternoon slump.
A power nap might help, as well, but combine the two and you may be in for a magical concoction of blissful rest.
During that 20 minutes you're getting some shut-eye, the caffeine has time to get into your bloodstream, and make you feel more alert when you wake.
However, there are three rules to the perfect coffee nap:
- You must drink the coffee (or anything with a similar amount of caffeine) immediately before napping.
- You must be tired enough to fall asleep right away, though the coffee-nap-combo still seems to work on study participants who only deeply rested.
- Do not sleep longer than 20 minutes or your brain may enter deeper sleep, thus making it more difficult to wake up and not feel tired.
If you want to know the science behind it all, Vox lays out all of the details here.
Vox references several studies, including one from UK-based Loughborough University, showing that participants who took a 15-minute coffee nap were more accurate on driving simulator tests than those who either drank coffee alone or who only took a nap.
Researchers of a separate Japanese study found that participants who drank caffeine before a nap were more successful on memory tests than those who took a nap and then either washed their faces or had bright light shone in their faces.
The bottom line, a nap gives you rest, while caffeine helps you feel more alert - and when you add the two together, you've got napping gold!