Focus: Exhausted? We all are. Britain has a sleep problem, and it's doing us serious damage

As research shows young mums are getting only three hours a night, Julia Stuart reveals what sleep deprivation is doing to the nation

We work too hard, as a nation, and don't take enough time off to recover. Then when we do put our heads down at night we can't sleep because of worries, noise, snoring partners or crying babies. Yes, you may yawn, we know all that. The question is, what is it doing to us? Brace yourself. It's not good news.

We work too hard, as a nation, and don't take enough time off to recover. Then when we do put our heads down at night we can't sleep because of worries, noise, snoring partners or crying babies. Yes, you may yawn, we know all that. The question is, what is it doing to us? Brace yourself. It's not good news.

Earlier this year, University of Surrey researchers reported that women aged between 40 and 59 are sleeping about six-and-a-half hours a night, 90 minutes less than they need. They blame fidgety, noisy men - many of whom are themselves not sleeping long or well enough. But now it seems women are getting even less sleep than Margaret Thatcher's famed four hours. A new study has shown that the average new mother gets just three-and-a-half hours' sleep a night compared with the five hours her mother enjoyed.

The finding was a result of a survey by the magazines Mother & Baby and Yours. Baby monitors that send parents leaping out of bed at the slightest gurgle and reluctance to put babies in a cot or leave them to cry are blamed. So too is the anxiety working mothers feel about getting a good night's sleep.

It's not just mums. One woman in five and one man in 10 reports being "abnormally" tired. And as any of them will testify, if you lie awake worrying that there are only five, or four, or three hours until the alarm goes off, there is no chance of getting to sleep.

All this can be highly dangerous, says Dr Louise Reyner of the sleep research centre at Loughborough University. Anyone who has to survive on three-and-a-half hours a night will soon feel serious effects. After a week you will not only feel very tired, but also have very poor concentration and have difficulty in planning or thinking for yourself. Your moods will also be disturbed. "I would argue that after one night of just three-and-a-half hours' sleep you should not be driving," says Dr Reyner. One in six car crashes that result in injury or death on major roads is caused by drivers falling asleep at the wheel.

After a month, the effects will become much more pronounced. "There will be severe concentration problems and difficulty remembering things," says Dr Reyner. "There will be general mood disturbances, which could lead to very severe mood swings. Women who have severe sleep deprivation tend to get postnatal depression. Their memory will be severely impaired and they will have trouble initiating behaviour."

You may also feel apathy, lack emotion, become distracted by irrelevant stimuli and suffer from inflexible thinking as well as impaired communication skills. Not good if you are attempting to feed, clothe, bathe and care for a vulnerable child, around the clock. "After a month of having such little sleep, a person is not in a fit state to look after a baby," says Dr Reyner. "It is very dangerous."

The amount of sleep we get each night has dropped by a fifth over the past century. In the West we get 500 fewer hours a year than we need, on average. Dr James Maas of Cornell University, New York, believes anyone having less than eight hours a night becomes "stupid" - a claim backed up by Canadian scientists who showed that the brains of people who don't get enough sleep actually shrink. A study of doctors in Denmark revealed that of those suffering from sleep disturbance, 30 per cent failed their final exams, compared with 10 per cent who slept well.

Research from the University of Chicago Medical Center also shows that sleep deprivation interferes with the body's ability to regulate insulin production and sugar metabolism, potentially increasing the risk of diabetes. Some scientists believe it decreases the production of leptin, a hormone that makes people feel full after eating. Without enough leptin, people continue to crave carbohydrates after they've eaten, which leads to weight gain and possible obesity. People who don't get enough sleep have also been found to have changes in their immune response and white blood cell production, which can lead to difficulty in fighting off infections.

So what happens if you try to survive on three-and-a-half hours sleep for more than a month, as some of us are doing? Dr Neil Stanley, director of sleep research at the University of Surrey, says it can be "disastrous for physical, mental and emotional health".

Even sleeping for one hour less than you need every night has major consequences, he says. "It increases your risk of obesity, because the more tired you are the more you crave sugary foods. And diabetes is linked to obesity. It increases your risk of heart disease, because the body needs the recuperation sleep provides. It increases your risk of depression because sleep is involved with dealing with the emotional baggage. It increases your risk of divorce, because you become tetchy, miserable and moody, and nobody wants to be married to someone like that. There's a body of evidence that not sleeping as much as you need does quite significantly increase your mortality risk."

And it's not just you at risk. Lack of sleep is said to have been a contributory factor in a number of disasters, including Chernobyl and the Challenger shuttle explosion. So go on, get your head down.

The new mother

'I feel kind of foggy all the time'

Sarah Brook, 38, from Harrow, has had very little sleep since her second son, Alex, was born 13 weeks ago.

"The longest amount of sleep I get in one stretch at the moment will be about three hours. That's on a good night. I might get about six hours altogether, but it's broken up into an hour here and half an hour's dozing there, and is just not as restful as a single stretch. I am exhausted. Lack of sleep makes me feel kind of foggy all the time, and drained. I'm often irritable and snappy, particularly with my husband, Peter. Luckily he's very understanding, but then he's tired as well. Some nights I'm just so exhausted that he does one of the night feeds for me, which I really appreciate.

"It also makes me hopelessly forgetful. When I worked as an HR director, before I had the children, I used to keep a whole week's appointments in my head, but now I have to write everything down. The other day I rang someone to say I couldn't make an appointment, only to discover it had been the day before.

"Clumsiness is another effect. I often drop things and the other day I walked into a door frame and banged my elbow badly. I'd never do anything like that normally, but being this tired just takes all the sharpness away.

"Because Alex is my second child, I know this will pass and I think I'm coping with it better than I did first time around. But I know I won't get a proper lie-in until Alex is old enough to get up and watch a video with his brother!"

The zombie

'I'd get shattered just walking to the shops'

Debbie Saunders, 45, from Tunbridge Wells in Kent, was woken every two hours in the night by her daughter for four-and-a-half years.

"Natasha fell into a pattern of waking every couple of hours from about six weeks old. At first she'd want milk, then as she got older it was usually just comforting, but it still took me between 20 minutes and half an hour to calm her down, every two hours throughout the night. I felt lucky if I got two hours at a stretch.

"Some days I felt so shattered it was like I was living in a haze, but you just have to keep going. I had no energy for anything and it made me short-tempered. I had very little patience with the people around me and even with myself.

"One of the worst effects was that I was so physically tired. I'd be exhausted just walking a mile or so up to the shops, which seems ridiculous now. I was also very forgetful.

"I used to long for sleep. Some days, I'd be nodding off on the sofa at 4pm when kids' TV was on. But at other times I'd get a second wind, which helped me get through. In a strange way, I got used to living like that.

"My doctor said Natasha might grow out of it when she started school, and sure enough her sleeping gradually got better. I've got so much more energy now and feel much better generally.

"You go through these things because you love your children. She was worth it. I don't think I could have lived with sleep deprivation for any other reason."

The Thatcher

'I lie awake with my brain racing'

Tony Hooley, 55, from Cambridge, is the founder and president of a digital speaker technology company. He survives, as Baroness Thatcher famously did, on just three to five hours' sleep a night

"I've been doing this as long as I can remember. I go to bed about midnight, then read for an hour or so to relax. But by three or four in the morning I'll be awake again. I'm thinking about work and all sorts of stuff - my brain just doesn't stop. So I either lie there thinking for a few hours, or I'll read until six or seven when it's not worth going back to sleep again.

"Sometimes I get up and spend an hour or two on the computer. I do find I can get a lot done some nights. I enjoy my work - I suppose you could say I'm driven by it.

"I am tired a lot of the time, but I don't really feel any other effects. I'm not particularly irritable or forgetful. Sleeping this way might slow me down a bit but it hasn't stopped me. You would think I'd catch up with my sleep on holiday but actually I usually sleep worse - I find a new bed or a new room very hard to get to sleep in. I went to my doctor and got some pills, which are supposed to relax me in the night and help to stop my brain racing, but I don't use them very often.

"I do get tired; often I feel I want to shut my eyes and have a rest in the day. When my company first started I worked from home and could doze for an hour in the afternoons, but that's not possible any more. I don't know if I'd perform better if I got more sleep. I'd like more, but I'm used to living this way now."