Sleep Disorders

Updated 11 December 2014

Just how much sleep is enough?

Everyone has differing needs when it comes to sleep. Some need more, some less but if you're falling asleep in less than 7 minutes after going to bed, you may be sleep-deprived.

There’s no magic amount of sleep required for optimal health. Each individual has different sleep needs, scientists at America’s National Sleep Foundation say. Some of us need just five hours a night; others can’t manage with fewer than 10.

The number varies with age. Babies should get about 16, teenagers up to nine and a half, and most adults between seven and eight hours a night.

Teenage sleep patterns differ from those of adults: it’s normal for teenagers to want to go to bed late and sleep late.

And while Granny sleeps lightly and for shorter periods she still needs as much deep sleep as she used to when she was younger. Her afternoon nap is important and she needs more sleep at night for sufficient deep rest.

Each individual has a basal sleep need, explains Dr Frans Hugo of the Panorama Psychiatry and Memory Clinic in Cape Town. Basal sleep need is the amount of sleep you require to rise refreshed and awake. If this isn’t satisfied a sleep debt builds up. Sleep debt is the amount of sleep you’ve lost. You feel and show the symptoms of sleep debt and deprivation when you’re awake.

Read: Extroverts are often sleep-deprived

Sleep debt

Most people fall asleep within 15 to 20 minutes of going to bed. If you fall asleep in fewer than seven minutes you have sleep deprivation, Dr Hugo says. Overworked people with sleep debt hit the bed like a sack of potatoes and say they went out like a light.

Adults need between six and eight hours of basal sleep a night but things get complicated when sleep debt starts to interfere with basal sleep need. A mother with a young baby may finally be able to sleep through several nights but the previous weeks’ lack of sleep means she will still be tired when she wakes up because of her accumulated sleep debt.

‘‘That’s why we have to accommodate the basal sleep need in a 24-hour cycle,’’ Dr Hugo says. The good news is researchers believe sleep debt can be reduced – provided sleep is made as much of a priority as eating. That’s why there’s merit in the claim a mom should sleep when her baby does.

Not getting enough sleep can affect your judgement and reflexes. Studies show medical students who suffer from a shortage of sleep make more mistakes. American scientists warn too little sleep has serious health implications.

Obesity, diabetes, heart disease, depression, drug abuse, learning disabilities and car accidents are all linked to sleep deprivation.

On the other hand too much sleep (more than 10 hours a night) can be a strong indication of depression and other conditions.

Read more:
Sleep deprivation tied to anxiety
Poor sleep affects the immune system
Sleep-deprived teenagers engage in risky behaviour

Image: Sleepy business women from Shutterstock

Compiled by Mari Hudson and Elise-Marie Tancred (reviewed January 2012)


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Sleep disorders expert

Dr Alison Bentley is a general practitioner who has consulted in sleep medicine and sleep disorders, in both adults and children of all ages, for almost 30 years. She also researches and publishes on a number of sleep-related topics both in formal research journals and lay publications including as editor of Sleep Matters, an educational newsletter on sleep disorders for doctors.

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