How much sleep do you need to stay healthy? From babies to pensioners

Is eight hours sleep still the golden rule? And how does optimal sleep differ for ages?

Just how much sleep should you and your kids get? Experts say the answer is vital to your health and wellbeing.

The old rule says eight hours a night is best. But in fact it depends largely on your age.

A new report from the US-based National Sleep Foundation illustrates the wildly varying amounts of shut-eye we need.

While someone 65 and over can get by on as little as five hours a night, a newborn baby may need as much as 19 hours a day.

And scientists warn that consistently ignoring guidelines can lead to conditions including obesity, heart disease, cancer and diabetes.

Here’s a breakdown of the ideal night’s sleep, whatever your age...

Newborns: 0-3 months

It seldom seems like it to frazzled new parents but their bundles of joy spend more than half their early months snoozing.

The ideal amount is 14 to 17 hours a day, though some need only 11 and others up to 19.

And boy do they need it. In the first few months of life sleep releases growth hormones crucial to physical development.

And babies are still learning while asleep. Dana Byrd, who wrote a Florida University report on how infants absorb what’s going on around them, said: “They are better learners, better ‘data sponges’ than we knew.”

Infants: 4-11 months

After four months your cherubs should have finally started to establish a sociable sleeping pattern that won’t leave you feeling permanently jetlagged. They take naps less often and sometimes sleep in one block through the night. Ideally they will have 15 hours, though they can get by on 10.

Babies still need more sleep than adults because their immune system is just starting to evolve and sleep provides the fuel.

Toddlers: 1 to 2 years

A tot that gets enough sleep may avoid turning into a screaming gargoyle on entering the “Terrible Twos.” Ideally, 12 to 15 hours.

Any less than 10 can make a child try to shake off lethargy by becoming hyperactive.

Studies even suggest that some children displaying symptoms of Attention Deficit Hyperactivity Disorder may, in fact, just need more snoozes.

Pre-school: 3 to 5

Once past those Terrible Twos you still have to stop your little angels turning into tired little demons.

Ideally they still need 10 to 13 hours, and absolutely no less than eight. Otherwise they can develop behavioural issues. A study by University College London found that kids who didn’t get the recommended amount of sleep could have emotional difficulties and problems relating to their schoolfriends.

School age: 6 to 13

More sleep leads to smarter kids, says a psychologist who tested 80 10-year-olds. Some had more sleep, others far less, and after three days he measured their ability to learn. The kids who had less sleep were the equivalent of two years behind their more alert counterparts in mental tests. Schoolkids need 9 to 11 hours a night, though it can be as low as seven or as high as 12.

Teenagers: 14 to 17

Adolescents aren’t lazy and grumpy just for the fun of it. Their mood­iness is often the result of not getting enough sleep.

With all the changes to the body brought on by puberty, a lot of sleep at this age is important to make sure their body releases the right amount of essential hormone, So they need to get eight to 10 hours a night at least.

One reason modern teens often get far less than this is their reliance on smartphones and tablets. The light emitted from hi-tech devices makes it harder for the brain to release melatonin, the sleep-promoting hormone.

A recent study in Norway found that two hours of screen time a night has a direct impact on how much sleep they will get.

Young adults: 18 to 25

It’s the time when some spend most of their time partying while others are in the process of starting a family or launching a career. For the latter two options more sleep is essential.

The ideal amount for a young adult is seven to nine hours, though six hours is good enough for some.

And while some high-flying executives brag about surviving on four hours night, most major achievers appreciate the value of a good night’s sleep.

As for starting a family, studies show that not getting enough rest can reduce a man’s sperm count by up to a third.

Adults: 26 to 64

The stress and demands of careers and families may make sleeping difficult, but if you want to enjoy the fruits of your labour, get some rest.

Adults need seven to nine hours, although cutting it down to six once in a while does no harm. While Margaret Thatcher famously boasted that she needed only four hours, for most people that would bring on all sorts of health issues.

A horror house of diseases are linked to a lack of adult sleep: strokes, obesity, diabetes, anxiety, depression as well as heart disease and cancer. We get even more prone to all of those as we get older.

A recent survey by Channel 4 found that sleep deprivation, ironically due to screaming babies, had been cited as a reason for three out of 10 divorces in Britain.

Older folk: 65 and over

Oldies are notorious for dozing off in the day. But that’s because they find it harder to sleep at night – and no one is entirely sure why.

But experts are sure people of retirement age must still try to get as much rest as they can.

Some can get by on five hours a night and others need nine. But getting a regular seven to eight hours can ward off all sorts of diseases, including dementia.

A surprising study by Stanford School of Medicine in California found that there was a much higher risk of suicide among adults aged 65 and above if they were deprived of sleep.