You know the feeling. It's the middle of the day — you're hitting that 3 p.m. wall and all you want to do is lay down for a nap. Sometimes, all you need is just a few minutes, but other times, you feel like you could sleep for several hours. However, if you're pressed for time and just need some shut-eye, 15 minutes may be all you have to catch some Zzzz's.

But, have you ever wondered how a 15-minute nap will affect you? Will you wake up feeling refreshed or even groggier than before? We took a look at the truth about the 15-minute cat nap, and what we found may surprise you.

15 Minutes is (Almost Always) All You Need

Based on NASA research, a nap should last between only 10 to 20 minutes. This type of nap provides significant benefit for improved alertness and performance without leaving you feeling groggy or interfering with nighttime sleep. In some cases, the longer you sleep (especially if it's for several hours), the more tired you will feel when you wake up.

Naps Can Have Psychological Benefits

Research shows that a nap can be a nice getaway for your mind and body, and allow you some peace from the craziness of your surroundings. The right nap will give you the rest and relaxation you deserve, resulting in lower stress and improved memory, and could even give you the boost you need to take on the rest of your busy day.

A Quick Power Nap Can Give You a Better Boost than Coffee

Sometimes coffee can act as a Band-Aid when you're feeling especially tired. However, experts say that caffeine can actually decrease memory performance, because the more wired you feel, the more likely you are to make mistakes. When you're feeling sleepy, try laying down for a quick nap instead of reaching for another cup. You'll be glad you did.

If you're feeling particularly tired, try incorporating a quick nap into your day. You'll be surprised at how much better you feel — and how rested you'll be — in just 15 minutes.