Home » The Science Behind Afternoon Naps: How Long You Should Nap

The Science Behind Afternoon Naps: How Long You Should Nap

by Melissa Bell
6 minutes read
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Is napping good or bad for your health? It turns out that naps can increase performance, restore alertness and reduce mistakes and accidents. Just make sure you don’t sleep more than 30 minutes, otherwise you’ll wake up feeling more tired than when you first laid down. Why? The science behind afternoon naps explains this phenomenon, and apparently it all about our brains.

Humans tend to sleep just once a day compared to over 85% of mammalian species that sleep more than once. Scientists still can’t determine whether we are naturally monophasic (sleeping once per day) or polyphasic (sleeping more than once per day), but it is clear that a great deal many of us aren’t getting enough sleep, since our bodies are telling us so.

If you find yourself in a sleep deficit, you may want to consider integrating some afternoon ‘power’ naps into your daily routine. But let’s see what exactly a ‘power’ nap is?

Infographic: Sleeping Is A Mix of Art and Science – Wallstreet Journal

Infographic: Sleeping Is A Mix of Art and Science – Wallstreet Journal

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Types of Naps

Power naps are sleep sessions that happen during the day between 1:00 – 4:00 pm. They should last between 10 and 30 minutes, because any longer and you run the risk of developing “sleep inertia” – that unpleasant groggy feeling, sometimes followed with headaches, that you get from napping too long. Why until 4:00 pm? Because sleeping past 4:00 pm will disrupt your regular night time sleep, so confining your naps in that particular time frame is important as well.

Dr. Sarah C. Mednick, a sleep researcher at the University of California, Riverside, breaks down the different afternoon naps for us:

10 – 20 minute ‘power’ naps:

This nap time is great for a quick energy boost and improved alertness. This sleeping length keeps you in the lighter stages of non-rapid eye movement (NREM) sleep, which makes it easier to go about your day after waking up.

30 minute ‘power’ naps:

Sleeping for 30 minutes may cause “sleep inertia,” the groggy-like feeling after waking up. This effect can last for up to 30 minutes and only afterwards can the nap’s restorative benefits become apparent. The reason this happens is because we are actually interrupting stages of entering into deep sleep, confusing our body and making us more tired.

60 minute naps:

The 60 minute nap, a favorite among students, is best if you want to improve your memory for facts, faces and names. It includes the deepest type of sleep, called slow-wave sleep. The downside is that you may feel groggy after waking up.

90 minute naps:

90 minutes is the time it takes for you to undergo a full sleep cycle, the lighter and deeper stages, including REM (rapid eye movement) sleep during which we start to dream. The 90 minute sleep cycle improves emotional and procedural memory (i.e., consolidating memory to riding a bike, playing the guitar) and creativity. Additional benefit of sleeping for 90 minutes instead of 30 or 60 minutes is the absence of sleep inertia, because you aren’t interrupting the 90-minute full sleep cycle (unlike with 30 and 60 minutes naps).

Napping at the Office?

Taking a nap is an excellent time for the brain to reboot – it helps increase mental alertness, learning, memory and performance. In 1995, NASA published a groundbreaking study that looked at the beneficial effects of napping on sleepy military pilots and astronauts. They found that a 40-minute nap improved performance by 34% and alertness by 100%. Planned naps are also extensively utilized in the medical community among nurses, doctors and medical students as studies show that napping improves performance and subjective report in physicians and nurses compared to no-nap conditions.

Indeed, napping while on the job is not a bad idea. Many companies like Google, Huffington Post, the Arizona Diamondbacks baseball teams all practice power naps during working hours. Many Japanese factories have sleeping rooms for workers and machine operators working on critical or dangerous machines that require constant alertness and attention.

Napping, Memory and Children

Napping also improves your working memory, which is responsible for the transient holding and processing of new and already-stored information and is important for reasoning, comprehension, learning and memory updating. Napping also improves memory retention, because when we sleep our recent memories are transferred to the neocortex and long-term memories are solidified and stored. This is one of the reasons daytime sleep is critical for effective learning in young children. Classroom naps boosts the learning capabilities of preschool children by enhancing the memories they acquired earlier in the day. Naps also help infants learn the rules of abstract language and when storing long-term memory. Studies conclude sleep-deprived children between the ages show more anxiety, less joy and interest and a poorer understanding of how to solve problems.

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Health Benefits of Napping

Napping greatly improves your overall health and mood. If you’re deprived of sleep, you’ll have an excess of the hormone cortisol pumping through your veins. Cortisol, the stress hormone, may help us deal with responses of the fight or flight manner, but excess of it also increases glucose intolerance, abdominal fat, weakens the immune system and muscular system, reduces memory and learning and decreases the growth hormone and testosterone levels in the body. As you sleep, your body releases growth hormone, which helps to boost the immune system, reduces stress and anxiety, gives your brain a chance to rest, and aids in weight loss and muscle repair. Sleeping and napping also saturates your brain with serotonin, reversing effects of anxiety, irritability and depression.

Daytime sleep can confer heart-related benefits by accelerating cardiovascular recovery after bouts of psychological stress. Researchers discovered that a 45 minute nap literally lowers blood pressure. For over six years, a research team tracked 23,681 people in Greece, none of whom suffered from coronary heart disease, stroke, or cancer. People who napped at least three times per week for an average of 30 minutes a day had a 37% lower chance of dying from a heart-related disease.

A 2008 study showed that naps are better than caffeine when it comes to improving verbal memory, motor skills, and perceptual learning. So the next time you are feeling groggy or tired, don’t reach for the coffee – take a 30 minute nap instead. You’ll feel better afterward!

Napping Tips

To get the most out of a power snooze, follow these quick tips from Dr. Mednick:

  • Be consistent. Keep a regular nap schedule. Prime napping time falls in the middle of the day, between 1 p.m. and 3 p.m.
  • Make it quick. Set your cell phone alarm for 30 minutes or less if you don’t want to wake up groggy.
  • Go dark. Nap in a dark room or wear an eye mask. Blocking out light helps you fall asleep faster.
  • Stay warm. Stash a blanket nearby to put over you because your body temperature drops while you snooze.



Read more about the power of napping here: Take a Nap! Change Your Life by Sarah C. Mednick, Ph.D

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