When you were a kid, you may have resisted the afternoon nap. But now that you’re an adult who may not be getting enough sleep, a daily nap sounds like an absolute dream. The good news is that the power nap is becoming more popular. In fact, more and more companies are recognizing its benefits, and those that are ahead of the curve encourage napping at work, providing nap rooms or nap pods where employees can get some shut-eye in the middle of a work day.

But what should you do if your company doesn’t have a dedicated space for a snooze? And why should you take a nap anyway?

Power Nap Benefits

Many people are not getting the required seven to nine hours of sleep per day, and this sleep deprivation can have many effects, like crankiness and a lack of focus. It can even become dangerous, like when you have to drive while you’re feeling groggy.

While it would be wonderful to get a full 90-minute cycle of sleep, it’s often not possible on a busy workday. So what’s a grown-up to do?

Enter the power nap. A power nap is a nap that lasts no longer than 30 minutes. Less than half an hour is enough to help you add to your sleep bank and reap some benefits:

Napping increases alertness. Don’t you just hate meetings after lunch? That’s typically when the yawns set in and it’s especially hard to focus. According to the U.S. National Sleep Foundation, naps “can restore alertness, enhance performance, and reduce mistakes and accidents.” It cites a study at NASA in which sleepy military pilots and astronauts reported increase alertness and improved performance after a nap. The foundation goes on to say that this increase in alertness can last for hours after the nap.

Napping can improve your memory. A study published in the journal Neurobiology of Learning and Memory found that a nap could greatly improve learning and memory. According to study leader Alex Mecklinger of the Experimental Neuropsychology Unit at Saarland, “A short nap at the office or in school is enough to significantly improve learning success. Wherever people are in a learning environment, we should think seriously about the positive effects of sleep.” Next time you have a seminar at the office, sneaking in a few zzz’s over lunch can help you retain all the info.

Napping may be good for your heart. Researchers from the Harvard School of Public Health were very interested in places that had siestas as part of their culture, as they had a lower incidence of cardiovascular mortality. Their large-scale study in Greece found that healthy men and women who took afternoon naps had a lower risk of dying from heart disease, and that working men in particular who took naps had a 64% lower risk of death from heart attacks and other heart-related conditions.

The researchers hypothesize that this could be because napping may provide a temporary escape from the stresses of work.

Napping can be good for your mental and emotional wellbeing. Anyone who’s suffered from a lack of sleep can attest that it can really affect your mood and, in extreme circumstances, lead to anxiety and an inability to function. A nap can feel like an indulgent mini-vacation that can relax and recharge you, and also improve your mood.

The Do’s and Don’ts of Power Naps

It’s not as simple as shutting your eyes when you feel the onset of sleepy symptoms. There are a few guidelines to help ensure that you make the most of your power nap:

DO take a page from the Spaniards’ siesta playbook and aim for a powernap between lunch time and 3 p.m. The human body’s circadian rhythm (sleep-wake cycle) takes a dip at around this time, making it an ideal power nap time.

DON’T sleep beyond 3 p.m. as this might make it harder for you to fall asleep at night.

DO keep it short—half an hour and below is ideal. A NASA study found that 26 minutes is the sweet spot, improving performance by 34% and alertness by 54%.

DON’T go beyond half an hour or you’ll reach the deep sleep cycle. Waking up in the middle of it will leave you feeling groggy and disoriented. Got lots of nap time on a weekend? Go for 90 minutes so you can complete the sleep cycle and still wake up feeling refreshed.

DO try having a pre-power nap coffee. It takes about 20 minutes for the effects of coffee to kick in, so you’ll get a double dose of energy when you wake up—from your nap and from the caffeine.

DON’T nap if you suffer from insomnia or other sleep disorders like sleep apnea.