Doctor: How much nap time is considered 'too much' - more harm than good?

Napping can boost alertness, improve mood, and boost productivity. However, sleeping the wrong way can do more harm than good.

Sleep researcher Dr. Talar Moukhtarian, Associate Professor of Psychology at Warwick University Medical School (UK), will explain clearly how to take a nap to be good for your health.

Napping is a double-edged sword, says Dr. Talar Moukhtarian. Done correctly, it can be an effective way to support mental and physical health. Done incorrectly, it can be harmful and even make it difficult to sleep well at night.

Napping is a double-edged sword. If done incorrectly, it can make you feel sluggish and have trouble sleeping at night.

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How long is too much nap time?

Dr Talar notes that napping for longer than 30 minutes can leave you feeling worse when you wake up. This is because of “sleep inertia” – the grogginess and disorientation that comes from waking up during a deep sleep phase, according to research journal The Conversation.

When a nap lasts longer than 30 minutes, the brain enters slow-wave sleep, making it much harder to wake up. Studies show that waking up from deep sleep can leave people feeling groggy for up to an hour.

What does science say?

Some studies show that excessive napping can even harm the heart and cause disease.

An analysis by the University of Tokyo (Japan) including 21 studies with 307,237 participants, found that napping for more than 40 minutes is associated with metabolic syndrome, including increased blood pressure, cholesterol and blood sugar, as well as excess fat around the waist, increasing the risk of heart disease.

People with chronic insomnia are often advised to avoid napping altogether, as daytime sleep can reduce their motivation to sleep at night.

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And a recent study by Ningbo University (China) also showed that napping for more than 30 minutes increases the risk of diabetes by 8-21%. For patients without diabetes, napping for more than 30 minutes can increase the risk of high HbA1c and impaired fasting glucose, thereby increasing the risk of diabetes later. For diabetic patients, prolonged napping can reduce blood sugar control and increase the risk of complications.

Additionally, Dr. Talar advises against napping too late in the day, as it can reduce sleep drive — the body's natural need for sleep — making it more difficult to fall asleep at night.

People with chronic insomnia should also consider napping. For some people, napping is necessary. However, people with chronic insomnia are often advised to avoid napping altogether, as daytime sleep can reduce their motivation to sleep at night.

How to take an effective nap

For an effective nap, timing and environment are important. Keeping naps to 10-20 minutes helps prevent drowsiness.

The ideal time is before 2 p.m. — napping too late can disrupt your body's natural sleep schedule, Dr. Talar advises, according to The Conversation.

Source: https://thanhnien.vn/bac-si-ngu-trua-bao-nhieu-la-qua-lieu-loi-bat-cap-hai-185250723144029173.htm