The daytime nap: how many minutes help and when it harms

After lunch, many people feel a dip in energy. This is not only about food: our internal daily rhythm has a natural fall in alertness in the early afternoon. In many Mediterranean cultures, including our own, a short rest at this time has long been a habit.

What studies say

In a 2009 review, the psychologists Catherine Milner and Kimberly Cote summarised research on daytime napping in adults. Short naps were linked with better alertness, reaction time, memory and mood, especially in people who had not slept enough at night. The effects were visible even in people who had slept normally.

Why length matters

When we sleep longer, we pass into the stages of deep sleep. If we wake from them, we feel heavy, slow and somewhat confused for several minutes up to half an hour. This is called sleep inertia. That is why a short nap, about 10–20 minutes, often gives a quicker benefit: we wake before going deep into sleep. A longer nap, about 60–90 minutes, may help memory more, but needs time to recover from after waking.

A good nap is not a substitute for the night. It is a small rest that helps the day go on.

When it can harm

• If you have insomnia. Daytime sleep can reduce the need for sleep in the evening and make falling asleep harder. In treating insomnia, it is often advised to avoid it.
• If it is too late. Naps after 3–4 pm are more likely to disturb night-time sleep.
• If it suddenly becomes very long and frequent. Some observational studies have linked long daytime naps in older adults with health problems. This does not mean napping causes them; it may be a sign of something else, such as poor night sleep or illness. If you feel a new and strong need to sleep during the day, talk to your doctor.

How to do it well

1. Choose the time: usually between 1 and 3 pm.
2. Set an alarm for 20 minutes. Even if you do not sleep, resting with your eyes closed has value.
3. Make the setting quiet: little light, little noise, a place where you can lie down or lean back.
4. After waking, get up, move a little, drink water and go into the light.