It's more effective than drinking coffee or taking a nap.

It's drinking coffee and then taking a nap.

It's called a coffee nap.

It might sound kind of crazy because most people realize that caffeine interferes with sleep.

But it takes a little while for the caffeine to affect you.

The caffeine has to go into your small intestine, pass into your bloodstream, and enter your brain. That takes about 20 minutes.

If you spend those 20 minutes unconscious, you're going to wake up feeling pretty great.

And to understand why, it helps to know what's making you feel groggy in the first place.

So there's a molecule inside your brain called adenosine, and it plugs into little receptors inside your brain cells and makes you feel tired.

Adenosine is a by-product of brain activity, so it builds up through the day and starts to slow down your neurons.

Caffeine chemically looks a whole lot like adenosine.

And when you ingest caffeine and it enters your brain, it blocks adenosine from fitting into those receptors.

A lot of people have said that this is like taking a car and putting a block of wood underneath the brake pedals.

Caffeine keeps your brain from slowing itself down.

The great thing about coffee naps is that sleep naturally clears out adenosine from the brain.

So the caffeine doesn't even need to compete with the adenosine to fit into those receptors.

So what's the evidence that this really works?

There're not a huge body of work but there are a few different studies.

When people took a 15-minute coffee nap, they went on to commit fewer errors in a driving simulator than when they only drank coffee or only took a nap.

As the test subjects were doing this really boring driving simulation, they were asked every 3 minutes to report their sleepiness level.

And the coffee nap group was consistently more alert.

Meanwhile, a Japanese study found that people who took a caffeine nap performed a lot better on a series of memory tests.

The challenge of the coffee nap is to time it just right.

You want to drink it quickly, so it—maybe you could do espresso shots or iced coffee if that makes it easier.

And then set an alarm before you fall asleep to wake up within 20 minutes,

because if you nap too long, you're much more likely to enter deeper stages of sleep, and you'll have what scientists call sleep inertia, which is basically grogginess.

If you have trouble falling asleep that quickly, the studies found that you can still benefit from the coffee nap.

Even just drinking the caffeine and getting a few minutes of restful half-sleep half-awakeness is going to make you feel more alert when you do get up 20 minutes later.