History is filled with great nappers:
Eleanor Roosevelt took naps before speaking engagements so she could face the audience with a refreshed mind.
Thomas Edison used to nap sitting up with a ball in his hand, so that when he dozed off the ball would hit the floor and wake him. (He did this because he found ideas that occurred to him as he was falling asleep were useful for his inventive efforts.)
Winston Churchill was also known to catch a few ZZZs during the day. He would often nap for one or two hours after lunch (Winnie liked his cocktails), but he also championed 20-minute naps, as he felt they provided all the refreshment he needed to prosecute the war.
As a med student, you probably also know how valuable naps can be, especially when it’s an exam week and you may not be getting the sleep you need. Grabbing a nap is a great way to refresh, improve your focus, and even give your memory a welcome boost. All that can only be good in the hyper-competitive world you live in.
That said, if naps aren’t done the right way, they can have unwanted consequences. These include sleep inertia, which is the groggy feeling you can have after waking up. And naps that are too long can interfere with your main sleep period during the night, which, in the long run, isn’t going to help you.
To make sure your naps are making you more and not less productive, we’re going to give you some tips on how to take a smart nap. As we’ll see, while no nap is perfect, if you’re looking to get the cognitive benefits of napping without too many downsides, Winston Churchill may have been on to something!
Some questions we’ll answer in this article include:
- Does napping really improve your learning and memory?
- Is it better to take a nap, cram, or take a break? Which is best for long-term memory a week later?
- Should you nap even if you don’t normally take naps?
- Should you nap even if you got a full night’s sleep?
- Is there an ideal nap length?
- Is there an ideal time to take a nap?
- Should you nap before or after class to maximize learning?
- Does napping make up for deficits in the previous night’s sleep?
- Should you nap if you normally have trouble falling asleep or staying asleep?
To put our discussion about how to nap the right way in context, let’s begin by taking a look at some basic sleep science. And if we’re going to learn how to build a smart nap, let’s start by having a look at the architectural blueprints.
Sleep Architecture in Humans
In human adults, sleep unfolds in the same pattern, be it day or night. It progresses in a series of stages: N1, N2, N3, and REM. In broad terms, sleep is classified as non-REM (stages N1, N2, and N3) and REM (when the majority of dreaming takes place). A full sleep cycle follows an N1, N2, N3, N2, and REM pattern. So in a full cycle, you pass through two stages of N2, one on the way into N3 sleep, and one on the way out of it before you enter dreamland.
A full cycle of sleep, from N1 through REM, takes between 90 and 110 minutes. On a typical night, we pass through the full cycle between four and six times. Waking up in the morning normally occurs during one final episode of dream-laden REM sleep.
Each stage of sleep has specific functions, and we spend a different amount of time in them as we cycle through the night. Obviously, when we take a nap during the day, we won’t pass through all of them unless we go through a full cycle. This is why naps of different lengths have different impacts on the body, and why at certain times, naps of a certain duration may be better than another.
Let’s briefly take a look at each stage of sleep and what happens during it, so we can understand how naps of different lengths can have different impacts on our bodies.
The Stages of Sleep
EEG monitoring is used to determine the state of wakefulness (or sleep) a person is in. For each stage of sleep, a certain brainwave (alpha, beta, theta, or delta) is considered typical.
How well we sleep and how long we spend in each stage of sleep can be affected by a number of things, including age, medication, circadian rhythm disorders, and brain injuries. As we noted in previous articles, many medical students suffer from anxiety and depression, which can also affect how we pass through the stages of sleep.
If you’re struggling with a mental health condition, be sure to talk to someone in student health services, or call the Physician Support Line to speak with psychiatrists who help doctors and medical students deal with mental health concerns. It’s free and you don’t need to be in a crisis to use it!
What follows is what happens in a healthy adult during each stage as they go through a complete cycle of sleep.
N1- Light Sleep – Theta Waves
5% of Total Sleep Time
Technically, falling asleep happens the moment low-amplitude mixed-frequency (LAMF) waves constitute more than 50% of EEG activity. At that point we enter N1. This is the lightest stage of sleep. During this time, theta brain waves are prevalent, skeletal muscles keep their muscle tone, and breathing is normal.
Stage 1 sleep lasts between one and seven minutes, and very brief naps (called micro naps) consist entirely of N1 sleep.
N1 sleep also appears to play a role in learning and memory, as demonstrated by the fact that waking people up during N1 sleep seems to promote forgetting. This may mean that very short naps can actually inhibit memory consolidation, because you disrupt the process as it’s starting.
On the other hand, it seems like Thomas Edison may have been on to something! It turns out that people who spend even a very brief period of time in N1 sleep (< 15 seconds) are more likely to come up with creative solutions to a problem. This effect was no longer evident when they went into a deeper phase of sleep.
So if you’re trying to solve a medical mystery, try taking a very short (< 5 minute) nap. Who knows, maybe you’ll have an important, life-saving insight!
N2 – Deeper Sleep – Sleep Spindles and K Complexes
45% of Total Sleep Time
N2 is a deeper stage of sleep and we spend about 45% of our time in this stage during a typical night. During N2, our heart rate and body temperature drop. This is the stage when teeth grinding (bruxism) takes place.
Sleep spindles—which are short bursts of brain activity thought to play an important role in memory consolidation—occur during N2 sleep. K complexes, the longest of brain waves, are also prominent during this sleep stage. They’re thought to protect sleep by preventing arousal in response to external stimuli.
Stage 2 sleep lasts around 25 minutes in the first cycle and that time increases with each additional cycle. So a 30-minute daytime nap will contain a full cycle of N1 and N2 sleep.
Numerous authorities on sleep, including many leading researchers and sleep foundations, say a nap that’s 20-30 minutes long is the ideal length! That’s because you’ll get many of the cognitive benefits that come with N1 and N2 sleep, without any of the downsides from napping for a longer period of time.
N3 – The Deepest Stage of Non-REM Sleep – Delta Waves
25% of Total Sleep Time
N3 sleep is also known as slow wave sleep. Sometimes it’s difficult to awaken someone when they’re in this stage, even with noises > 100 decibels. It’s during this stage people experience night terrors and sleepwalking. This also when the body strengthens the immune system, grows, and repairs itself. Stage 3 sleep lasts around 20-40 minutes, and the amount of time you spend in this stage decreases with each cycle.
A daytime nap that’s roughly an hour long will have around five minutes of N1 sleep, 25 minutes of N2 sleep, and 30 minutes of N3 sleep.
Naps of this length come with the same cognitive improvements we see with 20-30 minute naps, and they have some additional benefits that only a phase of N3 sleep can provide, such as body repair, growth, and improved immune functioning.
However, if someone is woken up during this stage, they usually exhibit sleep inertia, which can last from 30 minutes to an hour. During this time, mental performance can be moderately impaired until you fully recover from the nap.
REM – Dreaming and Wakeful Brain Wave Activity – Beta Waves
25% of Total Sleep Time
My Gen Xer brain automatically starts thinking about a certain band from Georgia whenever I see the acronym for rapid eye movement, but of course REM also refers to the final stage of the sleep cycle. Famous for its surrealness and lucid dreamscapes, this stage of sleep is characterized by beta waves and, strangely enough, has patterns of activity similar to wakefulness.
The first stage of REM starts around 90 minutes after you fall asleep and lasts about 10 minutes. As you cycle through the night, the amount of time you spend in REM increases, and the last stage can last up to an hour before you wake up.
Young adult naps, if of substantial length ( ≈ 90 minutes) will contain both NREM and REM sleep. Napping through the first REM cycle comes with a number of benefits, including processing emotional experiences, further memory consolidation, and possible creative insight.
To simplify all this for you, here’s a table that summarizes what you can expect to gain from napping for a particular length of time.
**Please note: these times are estimates based on averages. The only way to know exactly what stage of sleep someone is in is to look at their EEG data. How long each sleep stage lasts varies within a person from one sleep cycle to the next, and people can differ in how quickly they go through the stages of sleep.
| Nap Length | Stages of Sleep | Benefits | Downsides |
| < 5 Minutes | N1 | Possible creative insight, memory consolidation | Potential memory loss |
| ≈ 5-30 Minutes | N1-N2 | Improved memory, increased alertness without a period of sleep inertia | Won’t get additional benefits of napping longer |
| ≈ 30-60 Minutes | N1-N2-N3 | Memory consolidation, plus restoration and repair of N3 sleep. Once sleep inertia dissipates, you will be alert for longer. | Sleep inertia can make this less than ideal as a nap length. |
| ≈ 60-90 Minutes | N1-N2-N3-N2 | Additional benefits that come with a second phase of N2 sleep | It’s hard to tell exactly when you’ll go from N3 back to N2. Sleep inertia is a real possibility. |
| ≈ 90-110 Minutes | N1-N2-N3-N2-REM | All the benefits that come with a full cycle. A good idea if you’re trying to catch up on sleep and avoid sleep inertia. | Waking during REM sleep can cause sleep inertia. You’ll likely be back in N1 or N2 after 100 minutes or so. Napping too long can have a negative impact on nighttime sleep. |
Key takeaways:
💡 Micro naps (all N1 sleep) do have cognitive benefits, and may be useful when it comes to creative problem solving. Edison may have been on to something! If you’re trying to solve a problem in a creative way, try micro napping and see if it works.
💡 Churchill was right! A short nap that’s between 20 and 30 minutes long is best in many cases. It’ll give you most of the cognitive benefits that come from napping without the problems of napping for longer (i.e., sleep inertia, disrupting nighttime sleep).
💡 You want to avoid waking up during N3 or REM sleep, as either can result in sleep inertia. If this is a concern, try to avoid naps that are between 30 minutes and 90 minutes. If you’re trying to make up for lost sleep, go through a whole cycle (a nap around 100 minutes long) so you wake up in N1 or N2.
Three Ways to Beat Sleep Inertia
Many med students need to be alert after their nap, so here’s three things you can do to avoid sleep inertia upon waking:
1. Nap less than 30 minutes, for the reasons stated above.
2. Nap for around 100 to 110 minutes to make sure you pass through a full cycle of sleep and wake up during N1 or N2.
3. Take a caffeine nap! The way this works is you drink a caffeinated beverage before falling asleep. It shouldn’t interfere with dozing off, as caffeine usually takes ≈ 15-20 minutes to start affecting your nervous system. By the time you go into a deeper phase of sleep, the caffeine will really begin to kick in, so if you wake up during N3 or REM, you won’t suffer the ordinary effects of sleep inertia.
9 Key Questions About Napping
If you haven’t dozed off during this incredibly long article, thanks. Time to wrap it up! Let’s do that by answering some questions about napping and how to do it.
1. Does napping really improve your learning and memory?
Yes. You can expect to gain some cognitive benefits from even short naps, including improved problem solving, memory, focus, and alertness!
2. Should you nap, cram, or take a break when studying?
This study found that people who napped and crammed had better recall 30 minutes after learning than people who took a study break. A week later, people who napped had a better memory for test items than either group! It’s just one study, but it makes sense in light of all the other data out there.
3. Should you take a nap even if you don’t normally take them?
The data on this is mixed, but it seems even people who don’t normally take naps benefit from them. If you avoid napping because you wake up tired, it may be because you were waking up during N3 or even REM. If you’d like to give it another shot, try taking shorter naps and see if that helps.
4. What if you got a full night’s sleep? Should you still take a nap?
Yes, even people who get a full night’s sleep see benefits from taking naps.
5. Is there an ideal nap length?
As we said earlier, most experts agree that a 20-30 minute nap gives you the best bang for your buck. But your needs may vary. If you’re seriously sleep deprived, it’s best to go through a full cycle and shoot for ≈ 100-110 minutes. A nap this long can interfere with your sleep at night though, so it’s a good idea to do this early in the day.
6. Is there an ideal time to take a nap?
It turns out afternoon siestas probably aren’t just a cultural phenomenon, but are in fact deeply rooted in our biology. Early afternoon naps tap into a circadian rhythm dip that normally takes place after lunch. This makes taking a nap after your midday meal like Churchill did a pretty good idea, though the champagne lunch is probably less advisable.
Be careful though, as napping less than eight hours before bedtime or later than 3 p.m. can make it harder to go to bed at night.
7. Should you nap before or after class to maximize learning?
This is difficult to say as there are many factors involved, but most sources indicate napping fairly soon after learning is best for memory consolidation. Obviously, this won’t be feasible at times. If you need to nap before class or don’t have time to nap during the day don’t worry about it.
8. Does napping make up for getting a bad night’s sleep?
It can in some ways if you take a full cycle nap (≈ 100-110 minutes), but one can never fully make up for lost sleep.
9. Should I nap if I normally have trouble falling asleep or staying asleep?
It may not be the best idea, as it can potentially worsen insomnia.
Final Thoughts
If you’re in medical school, naps can definitely help you in many ways! Just keep the sleep cycle in mind so you can plan a smart nap and reap the benefits of it without too many of the downsides. A 20-30 minute nap is always a safe bet, but longer naps (full cycle) or shorter (i.e., the Edison nap) can also be of use depending on your particular needs. If insomnia is keeping you awake at night, please be sure to consult a sleep expert.
For more (free!) health tips for med students, check out these other posts:
