Over the years, our collective human experience has taught us that napping is a good thing. It rejuvenates us and actually makes our brains work better. Need evidence? Some of the greatest creative minds in history have been avid nappers, including Albert Einstein, Winston Churchill and Salvador Dali!

However, not all naps are created equal. And there’s something of a trick to napping so that you receive the most benefit and minimize the potential drawbacks. The timing and duration of a nap can mean the difference between having an energy-filled afternoon and being sluggish for the rest of the day.

Although your boss may not be pleased to find you napping at work, he or she may be well advised to consider what Churchill had to say about napping: “Don’t think you will be doing less work because you sleep during the day. That’s a foolish notion held by people who have no imaginations. You will be able to accomplish more. You get two days in one — well, at least one and a half.” You are likely to be far more productive after a short nap than you would have been by just struggling through the afternoon sleepiness that is natural to our circadian rhythms. We naturally become sleepy in the early afternoon, whether we have had a large lunch or not.

We are a chronically sleep-deprived society, with about a third of the population getting an inadequate amount of sleep on a regular basis. This decreases productivity and increases the risk of mistakes. There is a reason why there is an upsurge in the rate of car accidents the day after we lose an hour of sleep in spring when the clocks move forward. Even an hour less of sleep can make a difference in our cognitive ability. If you find yourself dreaming during a short nap of 20 minutes or less, it’s a sign that you are sleep deprived.

Scientists who study sleep explain what happens in our brain during the three different sleep cycles it goes through: The first two stages are called non-rapid eye movement (NREM) sleep, which lasts for about an hour, followed by rapid eye movement (REM) sleep, which lasts for 30 minutes or so (and is when we dream). The second stage of NREM sleep is the deepest sleep, referred to as slow-wave. If you awaken during this stage of sleep you are likely to feel groggy for a while.

Researchers recommend that your nap length should be dependent on what you are trying to accomplish. A nap of 10 to 20 minutes will boost alertness (great for pilots), a 60-minute nap will help to increase cognitive memory processing (a good idea before taking a big exam), and a 90-minute nap helps with emotional and procedural memory (learning to ski, for example) and boosts creativity.

Try to get your nap in between 1 PM and 4 PM, the time when your body is naturally sleepy, and when it won’t cause problems with falling asleep at night. Although the experts have not discovered an “ideal” nap length, Ilene Rosen, a sleep scientist from the University of Pennsylvania’s Perelman School of Medicine says a “10-to-20-minute nap is really the optimal time in terms of bang for your buck.”

Make yourself as comfortable as possible before napping, and use a light blanket if it helps you get to sleep. Set a timer so you do not oversleep. Sleeping partially upright and drinking a cup of coffee before your nap will help to ensure that you do not sleep too long and that you wake up perky and refreshed.