Drinking coffee before a nap is beneficial for brain functioning.

Researchers found that "coffee naps" may be the best way to maximize the efficacy of both sleep and caffeine, News.com.au reported. Although it sounds counterintuitive, a coffee nap -- having a coffee and then a 20-minute nap -- may be the best way to wake up, Counsel and Heal reported.

Conventional wisdom is that coffee serves as a stimulant and interferes with sleep.

"Caffeine is an impotent impostor: it binds with gusto, but fails to launch the all-important quieting message delivered by andenosine. Drinking caffeine is thus like putting a block of wood under one of the brain's primary brake pedals," author Stephen Braun explains in "Buzz: The Science and Lore of Alcohol and Caffeine," according to PIX 11 News.

Napping for 20 minutes after drinking coffee gives the caffeine time to go to work in the brain. However, there's more to it than simply killing time. It also has to do with how sleep and caffeine interact with a molecule in the brain called adenosine, which makes us feel drowsy, Newser.com reported.

After the caffeine is absorbed through the small intestine and passes into the bloodstream, it crosses into the brain. Once there, it fits into receptors 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," Vox reported.

The 20-minute nap ends just as the caffeine kicks in clears the brain of the molecule, maximizing one's alertness.

Previous studies have demonstrated how much more effective coffee naps are than just coffee or just naps.

Researchers at Loughborough University in the United Kingdom found that when tired participants took a 15-minute coffee nap, they committed fewer errors in a driving simulator than when they were given only coffee, or only took a nap (or were given a decaf placebo). They found that this was true even if they had trouble falling asleep, and just laid in bed half-asleep during the 15 minutesAnother study from Japanese researchers found that those who took a caffeine nap before taking a series of memory tests performed better on them "compared to people who solely took a nap, Vox reported.