There are so many reasons to love the world’s favorite legal stimulant. It’s invigorating, it smells like heaven, and apparently it might even help you live longer. (Tell that to the next person who comes between you and your morning brew.)

And if you travel in certain circles, you may have caught word of the now-legendary coffee nap, in which drinking coffee just before a midday snooze actually leaves you feeling more refreshed.

The science of coffee naps all comes down to the delicate balance of chemicals that circulate through your brain while you sleep.

As you ease into sleep, a chemical called adenosine binds to receptors in your brain. This little neurotransmitter slows down nerve activity, making you drowsy.

But when caffeine enters the scene, it effectively pushes adenosine out of the way, taking over the receptor for itself. So your nerve cells speed up rather than slow down — even though you don’t feel this while you’re asleep.

The net result? You wake up super alert and ready to crush everything in your path.

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Illustration by Brittany England

That’s the theory — but if your inner skeptic just woke up from their own nap, it’s a theory because it hasn’t been totally proven. Yes, there are plenty of holes in the coffee nap hypothesis.

But since we’re literally desperate for life hacks that’ll get us through the 3:00 p.m. slump, we dove into this coffee nap business with (hopeful) open minds. Read on to learn if you’re a born coffee napper and how to do it like a pro.

We know the news of a supercharged nap is exciting, but slow down and read these rules before you light the flame under the percolator.

Rule No. 1: Don’t try it too late in the day

You’ll want to time your coffee snooze for at least 6 hours before you turn in for the night. Studies show that ingesting caffeine too close to bedtime can disrupt your sleep.

Rule No. 2: Lie down as soon as you finish your mug

Caffeine starts to be take effect about 30 minutes after you drink it, so you’ll want to give yourself enough time to shut off that mental chatter and get to sleep before the caffeine starts working. For most of us, this takes 10 to 20 minutes.

If you need help relaxing into a nap, check out our guide to falling asleep fast.

Rule No. 3: Drink one or two cups for best results

Research has yet to nail down the exact amount of caffeine for the perfect coffee nap, but it appears that between 150 and 200 milligrams is the right amount. For most coffee brands, this works out to about two 8-ounce cups.

But since the whole point is to get to sleep before the caffeine kicks in, sticking to one cup might make the most logical sense (especially if you like to slowly sip your brew).

Rule No. 4: Set an alarm

Sleeping longer than about 20 minutes can send you into slow-wave sleep, which is much harder to wake up from than lighter sleep. The last thing you want is to feel groggy after a midday rest, coffee-boosted or otherwise.

While this all may sound counterintuitive at best (and pseudoscience-y at worst), a significant amount of research has been conducted on coffee naps. Since the ’90s, researchers have been looking at caffeine’s ability to enhance daytime rest.

Though most of the studies on coffee naps are pretty old and were conducted on small groups, their findings are pretty striking.

A 1996 study found that when 10 sleepy drivers drank coffee before a brief nap, they felt less sleepy, their driving was less impaired, and their brains showed fewer signs of drowsiness. (Drivers who simply took a break from the wheel didn’t feel more alert afterward — a scary testament to the need to pull over and actually sleep on road trips.)

Another compelling study from 1997 found that consuming caffeine before a nap energized 12 drivers far more than a placebo did. Interestingly, those who “non-sleep dozed” (meaning they weren’t able to fully fall asleep) after drinking coffee were just as energized as those who took a full-fledged nap.

The evidence for coffee naps doesn’t just apply to driving. Research on 68 night-shift workers confirmed that, compared to just sleep or just caffeine, the combination of the two was the most powerful pick-me-up.

In a 1994 study, 24 young men who completed addition problems and logical reasoning questions after a nap performed better when they drank 200 milligrams of coffee pre-snooze.

It probably won’t hurt to try! But if you’re not a natural napper, this isn’t going to be the magic bullet that turns you into one. And the added pressure to fall asleep within 20 minutes certainly won’t help.

This unorthodox sleep hack is best suited for people who can already nod off quickly and easily in the daytime.

Coffee naps are also probably less effective if you have an all-day coffee or tea habit. When your nervous system is constantly hopped up on caffeine, you’ll find it hard to plop down for an insta-nap. People with caffeine dependence have built up a tolerance to the substance, which makes it harder for them to reap the positive effects of coffee naps.

While the stakes are pretty low for trying out a coffee nap (worst-case scenario: You lie still for half an hour with a belly full of coffee), we suggest experimenting on the weekend when work isn’t on the line.

And if napping doesn’t come naturally to you, check out our guide to napping like a pro.

If it works for you, you’ve found a secret weapon for getting more out of daytime rest. And even if it doesn’t, can you really argue with an extra cup of coffee?

Sarah Garone is a nutritionist, freelance writer, and food blogger. Find her sharing down-to-earth nutrition info at A Love Letter to Food or follow her on Twitter.