Today's three-minute lesson

A Nap Borrows Sleep From Tonight

A nap can be exactly what you need after a poor night’s sleep.

It can improve your alertness, concentration and mood, making the rest of the day feel more manageable.

But sleep is not free.

We have already discussed adenosine - the substance that gradually builds in your brain while you are awake, increasing your sleep pressure as the day progresses.

When you nap, some of that sleep pressure is released.

That may be helpful in the moment, but it also means there is less pressure remaining when bedtime arrives.

This does not make napping bad.

The effect depends largely on when you nap, how long you sleep and whether you already struggle to fall asleep at night.

A short nap in the early afternoon is less likely to interfere with your sleep because it works with the natural dip in alertness that many people experience after lunch.

A longer or later nap can have a greater effect. You may enter deeper stages of sleep, wake feeling groggy, unsure what day it is, and find that you are not as sleepy when you go to bed.

If you regularly lie awake at night, a nap can also become part of an unhelpful cycle:

You sleep poorly, nap because you are tired, then reach bedtime without enough sleep pressure to fall asleep easily.

The next day, the cycle begins again.

Sometimes, you may need to tolerate a tired afternoon to give yourself the best chance of a better sleep that night.

Daylight, movement, fresh air and a change of activity can all help you remain alert without reducing your sleep pressure.

You could also try non-sleep deep rest, often shortened to NSDR.

NSDR is a broad term for practices that allow your body to become deeply relaxed while you remain awake. Yoga Nidra - a guided practice (which you can find on YouTube) sometimes described as “yogic sleep” - is one commonly used form of this kind of rest.

Listening to a short guided NSDR or Yoga Nidra practice may give you a chance to recover and recharge without actually falling asleep. It will not necessarily provide the same boost as a nap, but it can be a useful alternative when you need rest without reducing as much of the sleep pressure you are building for tonight.

If you do need a nap, try to take it in the early afternoon and keep it to around 20 minutes. Set an alarm so that a brief rest does not quietly become two hours of sleep.

Author Daniel Pink describes another option as a “nappuccino”: drink a coffee and then immediately take a short nap. Caffeine takes around 20 to 25 minutes to begin taking effect, so it may start working just as you wake from a 20-minute nap, combining the benefit of a brief sleep with the alerting effect of caffeine.

However, the coffee must still fall before your chosen caffeine cut-off - at least eight hours before bedtime. A nappuccino taken after that point may help you through the afternoon but make it harder to sleep that night.

The aim is not to ban naps.

It is to recognise that sleeping during the day affects how ready your body will be to sleep that night - and that sleep is not your only option when you need to rest.