Whether you’re looking for some extra energy to make it through a busy day, or are simply bored on a Sunday afternoon, sometimes you just need a nap.

But, you’ve probably had one of those naps where you wake up feeling more tired than you were before you fell asleep. Just like sleep, napping is way more complicated than dozing off and waking up.

“For most people, napping is a great way to recharge,” says Dr. Aarthi Ram, a neurologist specializing in sleep medicine at Houston Methodist. “Plus, naps can have really practical uses. For instance, napping can help combat drowsy driving, which results in 328,000 car crashes every year, according to the AAA Foundation for Traffic Safety.”

Dr. Ram says the overall benefits of napping include:

• Increased productivity and performance
• Improved mood
• Increased alertness
• Reduced levels of stress
  
  

In fact, a 1995 NASA study has shown that a nap can improve alertness by more than 50% and performance by more than 30%.

So why do some naps leave you feeling groggy when you wake up?

“Not all naps are created equal,” warns Dr. Ram. “There is such a thing as a bad nap, unfortunately, but avoiding one just takes a little bit of planning.”

When it comes to naps, timing is everything

If you’re thinking you can snooze for an hour on the couch and still wake up refreshed and ready to go, think again. Because, according to the NASA study referenced above, the ideal nap is only about 26 minutes.

In reality, Dr. Ram says there’s probably a window of time that’s best for each person — but the general rule of thumb is that the ideal nap is somewhere between 20 to 30 minutes.

The problem with a nap longer than 30 minutes is the risk of waking up while you’re in the deeper stages of sleep. At night, you need to be spending some quality time in deep sleep. During a nap, it’s the opposite.

“If you wake up from a nap while you’re in deep sleep, such as REM sleep, you experience what’s called sleep inertia,” Dr. Ram explains. “This is a groggy, disorienting feeling, which is probably the exact opposite of what you wanted to get out of your nap. Additionally, the effects of sleep inertia can take anywhere from 30 minutes to a few hours to recover from.”

It’s also important to consider the time of day before napping.

“If you take a nap too early in the morning, your body clock may get thrown out of whack — since your brain isn’t ready to be sleeping,” Dr. Ram explains. “And if you nap too late in the afternoon, it may interfere with your ability to fall asleep at your normal bed time.”

Dr. Ram recommends napping in the early afternoon, between 2 and 3 p.m.

3 tips for becoming a nap expert

If you’re looking to take power-napping to the next level, follow these tips:

1. Don’t let your nap run long. Dr. Ram recommends setting an alarm so you can be sure you’re not snoozing longer than 30 minutes.

2. Choose the right napping spot. Just like regular sleep, naps should be taken in a space that’s dark and quiet. If you can’t find a dark room, consider wearing a sleep mask. And if you can’t find somewhere quiet, drown out distracting noises by listening to white noise.

3. Nap in the early afternoon. Think of a nap like a dose of caffeine. If it seems too late in the afternoon for a cup of coffee, it’s probably also too late for a nap.