Should we fight off that after-lunch drowsiness with a cup of coffee or a power nap? Research suggests both!

According to scientists at Loughborough University, drinking coffee before a short nap, a so-called “coffee nap,” might exert beneficial effects in the brain. Results from two recent, small studies indicate that the coffee naps improve cognitive abilities. Combining the two daytime pick-me-ups produces more alertness and better cognitive abilities than drinking coffee or napping alone.

Researchers had tired participants perform activities in a driving simulator after coffee, a nap, or both. Those who drank coffee and then took a 15- to 20-minute nap made fewer errors in the simulator.

In a separate experiment, the researchers had 24 young male participants take short naps throughout a 24-hour period. They were instructed to not sleep as they normally would. Those who took coffee naps performed better on cognition tests compared with those who took naps right after having a coffee placebo that did not contain caffeine.

While these studies were not designed to prove a causal link between coffee naps and greater alertness, the researchers offer a plausible hypothesis for why the coffee naps work. A chemical in the brain called adenosine binds with receptors on brain cells and causes drowsiness. The activity of the brain cells that receive adenosine signaling decreases. Caffeine from coffee also binds to some of the adenosine receptors in the brain and blocks the drowsiness that adenosine causes.

Caffeine is a stimulant that takes about 20 minutes to begin producing its effects. Napping is a natural way to reduce brain adenosine concentrations. The researchers speculate that the combination of caffeine and the 20-minute nap sets the stage for maximal caffeine-induced stimulation by minimizing the brain’s adenosine signaling.

The idea of the coffee nap is not new. Several past studies have provided evidence that combining caffeine and an immediate short nap has noticeable positive effects on alertness.