SAN DIEGO -- A University of California, San Diego professor said it's a good idea to sleep on the job.

Professor Sara Mednick said that if you have a task that requires memory, your performance improves more after a nap than after you have a cup of coffee.

The trick is to keep your naps shorter than half an hour.

After 30 minutes, you fall into a deep sleep that can leave you groggy.

Mednick practices what she preaches.

She told 10News she naps at work.