Best length of Time for a Power Nap

Sleep phases

To find out what the best length of time is for a nap is, let’s first look at what the sleep phases of nighttime sleep look like and what processes occur during each of them:

Sleep phases are states of the brain involving its electrical activity. We distinguish two sleep phases:

• NREM (non-rapid eye movement, consists of 4 stages)
  
• REM (rapid eye movement, consists of 1 stage)

The sleep cycle begins with the 4 stages of the NREM phase and ends with REM sleep. The order of the sleep stages is as follows:

NREM1 → NREM2 → NREM3 → NREM4 → REM 

The entire cycle takes about 90 to 100 minutes and repeats about 5 times during nighttime sleep.

What sleep stage do we want to enter during power naps?

When taking your nap, you ultimately want to enter stage 2 of NREM sleep. That way, you won’t get into “Deep Sleep” (which you reach in stage 3 of NREM Sleep), but will still gain increased concentration and a better mood during the rest of the day. 

Skipping “Deep Sleep” may sound counterproductive to many, but in the context of power naps, it’s a good thing! 

After waking up from the third stage of NREM sleep without having undergone a full number of sleep cycles, you will actually feel sleepier than you did before your nap. this feeling of “muddling” can last for an hour or two after waking up.

This is also known as sleep inertia, and it’s counterproductive. After all, most of us are concerned with increasing productivity in our work/study. In this manner, stage 2 of NREM sleep is where you want to reach.

What happens during stage 2NREM sleep?

In the second stage of NREM sleep, eye movements gradually disappear, and muscle tension drops to minimal levels. Moreover, your body temperature drops significantly, and your heart rate slows down. During this sleep stage, the brain will start to cleanse itself of toxins, which will make you feel “fresh” after waking up, as after drinking a strong cup of coffee. 

It’s not so easy to wake up from 2NREM as you stop reacting to all outside stimuli. Therefore, having an alarm clock handy when power napping is indispensable.  

The 2NREM sleep stage usually lasts about 25 minutes but may last as short as 10 (especially for older/sick people).

The best length of time for a power nap

So far, we have reviewed the different phases of sleep and their stages. The next question is how much time does it take to enter the second stage of NREM sleep but avoid getting into the third stage. Or, in other words — what is the best duration for a nap without waking up tired?

10-min nap (a bit short)

Can a micro nap of 10 minutes cut it? – some of you who need the benefits that naps bring but don’t want to spend too much time on them would probably be thrilled if this was the best power nap length…. but it’s not. 

During a 10 minute nap, you will barely reach the first stage of NREM sleep, and our goal is to get to the second stage. 10 minutes of napping is better than nothing (see this study on the effect of ultra-short naps) but if you want to reach the optimal benefits of napping, you will need a few more minutes. 

15-min nap (good for fast sleepers)

A 15-min nap has some desirable effects. Here, you will just about enter the second stage of NREM sleep, and your body will begin to regenerate.

If you are doing a tough job (such as construction), this may be the perfect nap length for you, since due to exhaustion, you won’t need much time to fall asleep and will quickly enter the second stage of NREM sleep. However, if you are not able to fall asleep immediately, 15 minutes might still be on the short side.

20-min nap (Sleep expert’s choice)

A 20 minute power nap is suitable for most people. There is no chance that you will enter a “deep sleep” state within 20 minutes. Instead, you will be in the middle/end of the second stage of NREM sleep. And that’s what healthy napping is all about!  

After having reached the second stage of NREM sleep, your muscles will be much more relaxed, your body temperature will go down, and the quality of regeneration of your body and neurons will be much more noticeable. Adenosine and cortisol levels will also drop significantly, so after you wake up, your concentration will return to the level it was at the beginning of the day. 

It’s no coincidence that most sleep experts recommend 20 minute naps. While more or less may do it for some, 20 minutes is the sweet spot for most of us. 

30-min nap (risk of sleep inertia)

The longer the nap, the better? Well… not necessarily. 

A 30-minute nap is a pretty good option, but here, you are risking entering the third stage of NREM sleep, which you certainly want to avoid (you will get sleep hungover). 

Sure, a 30-minute nap can produce much better results than a 20-minute one, but it comes with the risk of sleep inertia. At 20-25 minutes, you’ll be highly likely to enter the second stage of NREM sleep, take advantage of its benefits, and miss the third stage of NREM sleep. 

90-min nap (only beneficial for the very sleep deprived)

During a 90-minute nap, you will go through the entire sleep cycle, which is 4 NREM phases and one REM phase. For many, this is far too long, and hardly the best length of time for a power nap. Such a long nap can give you trouble sleeping at night and therefore may disrupt your circadian rhythm. 

Is there even a group of people for whom a 90-minute nap will be the optimal option? – As it turns out, yes! There are two such groups:

1. People who have REM sleep deficits due to the medications they are taking. If you take any medicines that make it difficult for your brain to go into the REM phase at night, you may feel tired during the day. Your brain will somewhat “demand” more REM sleep, and in that case, a 90-minute nap could be a good option.

2. People that slept 3-4 hours less than usual at night. If you haven’t got a good night’s sleep like you usually do, it is rather apparent that you will be tired, and your concentration and mood the following day will not be optimal. In this  situation, you may want to try a 90-minute nap to provide your body with one extra sleep cycle. Just be mindful to avoid taking such a nap in the evening, and try to keep it to a maximum of 100 minutes to prevent disturbing your circadian rhythm and general sleep health!

Why nap?

Napping just doesn’t feel good – it does good too. Regular, short naps have a direct impact on how well we function as humans by increasing our alertness, cognition and overall mood. There are also important long term benefits of daytime naps including reduced risk of coronary heart disease and burn-out.

On top of all this, napping can benefit the economy. Studies show that sleep deprived workers costs businesses large sums of money every year, so making the time for a nap during the workday is really worthwhile. This is the reason more and more businesses are investing in sleep tech such as nap pods.

Develop your nap routine

For most people, the optimal power nap length will be between 20 and 25 minutes. That being said, a significant factor will be how much time you need to enter the first stage of NREM sleep. 

If you are tired and there is not much noise around you, it may take you less than 5 minutes. However, if the conditions for falling asleep are less than ideal, you will likely need more time for your nap.

Like so many things, developing a strong napping routine takes practice and consistency. Figure out how much time you need to fall asleep and devote the same point of each day to napping to develop strong sleep patterns. In time, as your ability to drift off quickly increases, you will need less time to achieve the perfect nap.

Sources

“Brain Basics: Understanding Sleep”, Office of Communications and Public Liaison, National Institute of Neurological Disorders and Stroke, US National Institutes of Health, 2017

“Power Sleep”, Dr. James B. Maas, 1998

“Siestas and your heart: Can you nap your way to health?”, Harvard Medical School, 2008

“Day-to-day variability in sleep parameters and depression risk: a prospective cohort study of training physicians”, Daniel B. Forger, Elena Frank, Srijan Sen, Cathy Goldstein, 2021

“Older People Sleep Less. Now We Know Why”, Anna Almendrala, 2014