The Science of Napping
How long should my nap be? What is the perfect nap time of day? How do I get a deep nap that doesn’t leave me feeling groggy? Can naps make up for a lack of sleep?
These are common questions that have a scientific answer. There are different types of naps that are optimal based on your sleep needs, anticipated sleep needs, and the time of day.
Napping is one of the best (and easiest!) things that you can do for your health, work performance, and general well-being. Scientific evidence has shown that napping can improve waking performance and alertness, even after a normal night of sleep. It is the best way to counteract that grogginess that occurs when you’re sleep deprived or feel tired at 4 pm when your circadian alertness decreases.
Napping can be immensely helpful to your work life and your day, but napping the wrong way can leave you feeling drowsy and grumpy. Keeping the following guidelines in mind can help you avoid these negative side effects.
In general, it’s best to avoid waking up during the deep sleep phase. The ideal time for a short nap is under 30 minutes or over 90 minutes, so that your body isn’t in deep sleep when you wake up. The danger zone of napping is between 30 to 80 minutes. If you wake up during this window, it’s likely that you’re waking up during the deep sleep cycle. This will leave you feeling groggy and confused when you awaken, keeping you from feeling refreshed.
It’s also best to nap when the circadian component of sleep is low so that it doesn’t take long to fall asleep. Try to nap in early afternoon during your circadian dip. Late afternoon naps can keep you from falling asleep that night.
Different types of naps are appropriate for different circumstances. Replacement Naps are best for when you are sleep deprived, Appetitive Naps help to improve performance, and Prophylactic Naps are used in preparation for sleep deprivation.
Replacement Naps / A Full Sleep Cycle Nap
Replacement Naps are taken to make up for previous sleep loss. These naps should be long to ensure the restorative powers of a complete sleep cycle. For example, if you are sleep deprived and you feel tired, a longer nap of about 90 minutes may be appropriate. A 90 minute nap means that you will likely go through an entire sleep cycle. Sleeping for an entire sleep cycle will help you feel refreshed and more alert, while also ensuring that you do not awaken in deep sleep.
If you are not sleep deprived, then shorter naps of less than 30 minutes are best. These are called Appetitive Naps. In a recent study, people who took less than 20-minute naps in the mid-afternoon experienced increased work performance and rated themselves as being less tired.
The best time to take a nap can also be influenced by how long you plan to be awake. If you know that you are going to stay awake for a long period of time, taking a nap prior to this period of sleep deprivation can improve your performance. These types of naps that are taken in advance of sustained wakefulness are known as Prophylactic Naps. The key to these naps is to sleep before the period of sleep deprivation. Taking prophylactic naps can help keep you alert and focused.