It might sound crazy: conventional wisdom is that caffeine interferes with sleep. But if you caffeinate immediately before napping and sleep for 20 minutes or less, you can exploit a quirk in the way both sleep and caffeine affect your brain to maximize alertness. Here’s the science behind the idea.
To understand a coffee nap, you have to understand how caffeine affects you. After it’s absorbed through your small intestine and passes into your bloodstream, it crosses into your brain. There, it fits into receptors that are normally filled by a similarly-shaped molecule, called adenosine.
Adenosine is a byproduct of brain activity, and when it accumulates at high enough levels, it plugs into these receptors and makes you feel tired. But with the caffeine blocking the receptors, it’s unable to do so. As Stephen R. Braun writes in Buzz: the Science and Lore of Alcohol and Caffeine, it’s like “putting a block of wood under one of the brain’s primary brake pedals.
Read the full, original story: Scientists agree: Coffee naps are better than coffee or naps alone