Is it OK to nap? Napping borrows from the sleep you'd use at night

If you've wondered whether a 15-minute nap after lunch is OK, or why nights are hard after a two-hour weekend nap

Key points in 30 seconds

1. While you're awake, sleep pressure builds up in your brain, and at night that pressure helps you fall into deep sleep. A nap uses up some of that pressure ahead of time.
2. If you have insomnia, the basic rule is to cut back on naps. "I didn't sleep last night, so I'll at least take a nap" is the most common way insomnia keeps going.
3. On days when your night sleep is fine but you're short on sleep, or when you have to drive while drowsy, a short nap helps.
4. There are three rules: under 20 minutes, early in the afternoon, and somewhere other than your bed.
5. If you sleep enough but are unbearably sleepy during the day and snore heavily, a sleep apnea test comes first.

What we often hear

• "After lunch, my eyelids start drooping."
• "I hold off on napping because I'm afraid I won't sleep at night."
• "After sleeping two hours on the couch on the weekend, my head feels even heavier."
• "The day after a bad night, I feel like I need a nap just to get through."

After lunch, your eyelids start to droop.

It feels like 15 minutes with your head down on the desk would bring your afternoon back to life, but at the same time you worry. Won't napping make it harder to sleep at night? On weekends you pass out on the couch for two hours, but when you wake up your head feels even heavier, and that night you toss and turn without fail. Are naps a tonic or a poison?

The answer depends on who naps, when and for how many minutes. Let's start with the one principle that decides it.

How does sleep come?

Body clock researchers explain why we get sleepy with two forces.

• The body clock, which tells the time of day
• Sleep pressure, which builds up little by little in the brain while you're awake

When you wake up in the morning, the pressure starts near zero and fills up until evening, in proportion to how long you've been awake. You fall into deep sleep at night because this pressure has risen high enough. It's like sand piling up in the top of an hourglass all day, then pouring down at night.

A nap pours out a little of that sand ahead of time. That's also why your head clears after a short nap: the pressure has gone down. And for exactly that reason, if you nap for a long time, there isn't enough sand left to pour at night. You lie down, and sleep won't come.

Whether a nap is a tonic or a poison comes down to how much of the pressure meant for the night you've used up early.

What should I do about naps if I have insomnia?

The basic rule is to cut back.

Specialist books on insomnia treatment include limiting naps among the basic rules of treatment. When someone who can't sleep at night releases the pressure with a nap, sleep comes even harder that night, they're sleepier the next day, and they nap again: a loop forms.

There's one thought that specialist books single out as needing correction.

"I didn't sleep last night, so I need a nap today to function properly."

This kind of making up steals the night's pressure again, and is the most common way insomnia keeps going. It's natural to be sleepy the day after a bad night. If you carry that pressure through to the night instead of using it during the day, you're likely to fall asleep faster and more deeply than usual that night. This is the key to breaking insomnia.

If you feel every day that you absolutely need an afternoon nap to work properly, specialist books see that as a sign that your night sleep is short or your body's rhythm is off. The thing to fix is the night, not to nap more.

Are there times when a nap helps?

There certainly are.

• Days when your night sleep is fine, but you're short on sleep because of working late, caring for a baby or shift work
• When you have to drive in the afternoon and feel drowsy

In these cases, a short nap releases just the right amount of pressure, prevents accidents and saves your afternoon. Specialist books on the body clock also recommend short naps at times like these. But there are conditions.

How should I nap?

First, under 20 minutes. The nap length specialist books recommend is 20 minutes or less. Any longer and you enter deep sleep, and when you wake up you actually feel groggier and heavier. That's the sleep inertia we described in Feeling groggy in the morning isn't proof that you slept badly last night. The longer it is, the more of the night's pressure it steals too. Set an alarm for 20 minutes, and sleep leaning back in a chair or sitting on the couch. Not lying down keeps you from going too deep.

For people whose night sleep is shattered by severe pain, specialist books sometimes make an exception and allow 30–45 minutes. That's something to decide together at your visit.

Second, early in the afternoon. A nap close to evening directly steals the night's pressure. A commonly recommended cutoff is before 3 p.m. If you get sleepy after that, get through it by moving around or getting some light outdoors instead of napping.

Third, don't nap in bed. Your bed is the place for night sleep. A habit of lying down in bed to sleep during the day blurs the link "bed = sleep" and disturbs your night sleep too. Take naps on the couch or in a chair.

Why do naps increase with age?

Specialist books on the body clock explain that as we age, the clock's signal weakens, so we tend to be sleepy during the day and wakeful at night. That's why long naps in older adults break up night sleep even more, and broken night sleep in turn calls for more naps.

If you're an older adult, decide ahead of time what to do instead of napping when you feel sleepy during the day (a walk, a get-together, household chores), and if you still need a nap, keep to the 20-minute rule. There's more on age and sleep in Is it normal to sleep less as you get older?.

Daytime sleepiness like this isn't solved with nap rules

• If you're unbearably sleepy during the day even though you slept enough at night, and you snore heavily or have been told you seem to stop breathing, a sleep apnea test comes first.
• If you sometimes suddenly fall asleep during the day as if collapsing, other sleep disorders need to be checked.
• If your mood has been low for more than two weeks and your naps have gotten longer, we also recommend seeing someone for your mental health.

How we work

First, we look at your naps and night sleep together. If you bring a 1–2 week sleep diary that records your night sleep along with how many naps you took and how long, we can see how much your naps are stealing from the night's pressure, and whether a problem at night is calling for naps. We also look at what's causing your daytime fatigue with blood tests and abdominal and pulse diagnosis.

Second, we make sure pressure builds up for the night. Together we build a daily schedule with nap rules (length, timing, place), a fixed wake-up time, morning light and daytime activity. We use acupuncture and pharmacopuncture (herbal acupuncture), and herbal medicine matched to your tests, to manage daytime fatigue and nighttime alertness. If you spend a long time lying wide awake in bed at night, we also do bed retraining together.

Third, we check with the diary. Together we see whether you fall asleep faster at night as your naps decrease. We don't treat without evidence.

What changes

An afternoon when you cut your after-lunch drowsiness to 20 minutes and stay clear-headed. Days when, thanks to that, you fall asleep faster and more deeply at night. A day when daytime and nighttime don't steal each other's sleep.

That's what we aim for.

Whether you need a nap or should cut back differs from person to person, depending on your night sleep, your lifestyle and your age.

Today's takeaway

A nap borrows from the sleep you'd use at night. If you have insomnia, cut back. If you really need one, take it early in the afternoon, for under 20 minutes, outside your bed.

There's just one thing to do today. For a week, write down how many naps you took, for how many minutes and where. Even a quick doze on the couch. If you write next to it how long it took to fall asleep that night, you'll start to see how much your naps are borrowing from your night sleep. Bring that record with you, and we'll look at the rest together. We're open until 8:30 p.m. on weekdays, and on weekends and public holidays too.

The evidence for insomnia treatment is summarized in the director's column Waking up during the night is insomnia too.

For questions or appointments, message us in English through the messenger at the bottom right of the page, or call +82-53-716-1175.