This study skill is similar, yet different from the last study skill. Naps can give you a quick boost of energy which helps you keep studying. Short 10-20 minute naps can boost alertness and cognitive function. Longer 60-90 minutes naps can help you hit “save” on the information you are studying, but can run the risk of making you groggy or upsetting your nighttime sleep. I’ve had many a study session saved by a short nap.

Source:

https://www.newscientist.com/article/mg23030750-800-how-can-i-nap-like-a-pro/