Coffee and sleep mesh together about as well as Tom and Jerry, Superman and Lex Luther, Diet Coke and Mentos.

Even so, the latest life hack blowing up the Internet is coffee naps.

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Dominique Ellis of New Orleans is a devotee. After opening her own eponymous PR shop, this young professional found herself on call (and tired) 24/7.

A “coffee nap” is a 15-to-20-minute nap taken immediately after consuming a cup of coffee.

“I read a study about people who down a coffee and then take a power nap to increase their nap’s productivity and decided to give it a try,” Ellis told LifeZette. “I’m not sure if it’s 100 percent physically beneficial or if some of it is psychosomatic, but it’s been working for me for the last four months.”

Added Ellis, “My motto is, whatever works.”

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A “coffee nap” is a 15-to-20-minute nap taken immediately after consuming a cup of coffee. In a short nap, your brain won’t enter the deep stages of the sleep cycle. Meanwhile, the caffeine from coffee takes at least 20 minutes to reach your brain, as it must be absorbed into the bloodstream through the small intestine. Then it must cross the blood-brain barrier to take effect, according to the National Center for Biotechnology Information.

The caffeine from coffee takes at least 20 minutes to reach your brain.

Once in the brain, it settles into receptors shaped to fit adenosine, a neuro-modulator that causes sleepiness. The caffeine blocks adenosine, therefore promoting wakefulness. A favorite simile from Stephen R. Braun’s 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.”

Sleep of any kind — a nap or an overnight slumber — helps remove the adenosine from your brain. The idea behind a coffee nap is that the coffee will fill these receptors at the moment they’re mostly empty, simulating that first cup of Joe in the morning.

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Related: Coffee’s Impact on Hormones

As Ellis mused, the effects may be physical or placebo.

There is some research to back up the notion of coffee naps’ effectiveness — a few studies from Loughborough University and one from Japan, though none of these contained more than 12 subjects. The Loughborough studies looked at a coffee nap versus either coffee or a nap, while the latter pitted a coffee nap against a nap containing other outside stimuli (such as light shining in subjects’ eyes, or water splashed on their faces).

These are hardly conclusive, however; both naps and caffeine promote wakefulness.

“There is no pill, substance, drug, or exercise that can replace lost sleep.”

Dr. David Dinges, chief of the Division of Sleep and Chronobiology Department at University of Pennsylvania’s Perelman School of Medicine, said that coffee naps are “not more beneficial, based on the data to date.”

Related: Best Sleep Tips for Families

Dr. Gary Zammit, executive director of the Sleep Disorders Institute and a clinical associate professor at the Columbia University College of Physicians and Surgeons, remained similarly unconvinced.

“In my mind, it really is counterintuitive to take caffeine before a nap,” Zammit said in an interview with LifeZette.

There are three types of naps, he said: casual, recovery, and prophylactic. Casual naps occur when you’re lounging in a lawn chair, getting a suntan, and doze off. Recovery naps are taken to catch up on a sleep after a night of getting too little, while prophylactic naps are taken in anticipation of expected sleep loss.

If one receives enough sleep, a nap becomes wholly unnecessary, and Zammit suggested that rather than focus on fads like coffee naps — which are taken when people are sleepy and thus already somewhat impaired — people should simply focus on getting more sleep.

“The only thing that replaces lost sleep is sleep,” said Zammit. “There is no pill, substance, drug, or exercise that can replace lost sleep.”