Suffer sleepless nights? Can't get out of bed? Katy Guest meets the experts who are finally unravelling the mysteries of the Land of Nod

Napoleon Bonaparte, who was not a good sleeper, advocated "six hours sleep for a man, seven for a woman and eight for a fool". Two hundred years later, things are a little more confused.

According to a new survey, we are a nation of insomniacs: almost half of Britons say they get less than five hours' sleep a night; 65 per cent have trouble sleeping and four out of five do not feel refreshed when they wake. They claim to be suffering from chronic lack of sleep.

But these people are about to get a rude awakening. The author of a new book, Sleepfaring, would like to debunk some of the ideas surrounding "sleep debt". Professor Jim Horne is the director of the Sleep Centre at Loughborough University and edits the Journal of Sleep Research; he says that claims we are all going through life on the verge of nervous collapse are nonsense - and that the "recommended" eight hours is a myth. So are half of British people fools?

"There is no evidence that we are getting less sleep than we used to," says Professor Horne. "The survey, by GMTV, said that 65 per cent of people have trouble sleeping. I have not found that. Of course, if you ask people whether they would like more sleep, most say yes. But if you ask them what they would do with an extra hour a day, most wouldn't use it to sleep."

What Professor Horne suspects is that people are not failing to sleep enough, but failing to sleep right. "A very few people are naturally short sleepers: five hours or less," he says. "A very few are naturally long sleepers: nine hours or more. But for everyone else it is the quality of sleep, not the quantity, that is important. Six hours of uninterrupted sleep are much better than nine hours of interrupted sleep."

Stephen Emegbo, a sleep physiologist at the University of Surrey's Sleep Research Centre, agrees. "Everybody is as individual as a thumbprint when it comes to how much sleep we need," he says. "People like Thatcher and Churchill famously claimed to perform well on five hours' sleep a night; but put somebody else on that and they won't be able to perform. Older people need less sleep than younger people. And women tend to have more slow-wave or restorative sleep than men."

He does, however, stress the importance of "sleep hygiene" - keeping your bedroom cool, dark and free from televisions and stimulating electrical equipment. "People forget how important sleep really is. If people keep working 16- or 18-hour days their vigilance and performance will be affected and health issues will begin to show."

This belief is borne out by the statistics. According to the Royal Society for the Prevention of Accidents, 20 per cent of accidents on motorways are caused by tiredness, and more than 300 people are killed each year by drivers falling asleep at the wheel. The relationship organisation, Relate, believes that sleep disorders are the underlying cause of many relationship break-ups.

Many sleep disorders go undiagnosed: problems such as sleep apnoea, where the patient is woken by interrupted breathing, or restless legs, where twitching or crawling sensations interfere with sleep, are easy to "get used to", according to Professor Horne. Mr Emegbo worries that "most people going to their GP do not report difficulty sleeping as their primary issue: they think it is the norm." Professor Horne advises insomniacs not to go to bed until they are sleepy, and to try doing a jigsaw instead: "there's something particular about using the eyes and hands, and it makes the eyelids feel heavy. Going to bed in a relaxed state of mind is more important than anything else."

But if you are stilltired after an eight-hour night, you could be one of the 2 per cent with an undiagnosed sleep disorder; and you are in good company. Emegbo cites the example of Fat Joe in Dickens's Pickwick Papers: the child who fell asleep standing up. "I would diagnose sleep apnoea," he says. "We see that a lot." Reassuringly, this is not such a modern phenomenon. And perhaps we are not fools after all.

The Napper

Andy Bartlett, 33, product designer,, Newquay

I've got two young children and my wife's with them all day, so the only time I can make a contribution is in the evenings and at night. I only get five hours' sleep because I'm up a lot feeding the kids and settling them. If I have a big sleep I feel groggy, whereas a nap takes the edge off the tiredness and helps me get stuck into the rest of the day.

In meetings I sit in the darkest corner, open my book, pen in hand, and get a bit of shut-eye. The skill I've developed is to listen just enough so that if your project comes up you can snap out of it. In a meeting I can only get away with a couple of minutes at a time, but other naps can last between 20 minutes and half an hour. Having naps means I am less grumpy and tired and can help my family a bit more. It's win at home and win at work as well.

National Nap at Work Week ends today

The Insomniac

Carrie Frain, 25, transport officer, London

According to my mum I haven't slept through the night since I was born, but about seven years ago it got much worse. On a typical night I go to bed when I'm tired, toss and turn for a bit and then get up to watch some telly. I am up and down all night, getting something to eat, tidying up and sorting out the house until I eventually feel tired enough to drop off. I usually get about two to four hours' sleep a night.

Getting through work on no sleep is very hard and for a while I just refused to get out of bed in the morning because I was so exhausted. I was so run down that I started suffering from recurring ear infections and colds; and then the panic attacks started because I was so tired. If I haven't slept for a couple of days I tend to get really angry, then I get very emotional.

I've tried all sorts of remedies to help me sleep - herbal and non-herbal, I've tried sleeping pills, lavender and they haven't had any effect, so I have just learnt to adapt to my insomnia and now I'm managing to cope a bit better. I just have to keep telling myself that eventually I will get some sleep and accept the way I am and keep going.

The Pill Popper

Juliette Meeus, 45, television news producer, London

I wake up in the middle of the night and stay awake for hours thinking, worrying or feeling stressed, so I take sleeping pills so I can function the next day. I've been taking them on and off for six years, whether it's an antihistamine, over-the-counter medication, or something prescribed. It makes me feel good to have them around - as a sort of crutch.

I try not to take them every day as they're addictive and I don't want to become too reliant on them, and I don't know enough about what the effects of long-term use are, but I take them a good three times a week. And the older I get, the less over-the-counter stuff works for me.

I don't take sleeping pills on the weekends because I don't feel the same pressure to have a good night's sleep, but during the week I need six hours, if not more, because I have to get up at 4.45 in the morning. If I don't sleep for a couple of days I feel really ragged, it affects my personality, my mental health, and every area of my life, so having them makes me feel there's some recourse for me.

The Sleepwalker

Debby Colburn, 34, carer, Marlborough

When I was 13 or 14 I vividly remember my parents coming downstairs one morning and finding all the doors unlocked and it was then we realised I must have walked downstairs in the middle of the night and unlocked them in my sleep.

More recently I've been waking up by the bedroom window with the curtain open, or at the window in the front room. I feel so stupid when I realise that I've been sleep walking and think, "Why on earth have I done this?" It can be embarrassing. If I walk out of the bedroom door and suddenly wake up, quite often my husband wakes up too and asks me where I'm going, so I just say, "Oh I've just been to the loo," knowing full well that I've been walking in my sleep.

At work sometimes we have to do sleep-ins at the residential homes. I am responsible for looking after people and I worry that I could end up locking myself out of the house and wake up in the street in my pyjamas. I don't have a clue why I do it, but sleep-walking is just part of my life now.

The Heavy Sleeper

Lawrence Weyman-Jones, 23, student, London

Since going to university I seem to have evolved into somebody who needs a lot of sleep - about 11 hours a night. Most days I wake up at about midday and when I don't get enough sleep I feel very irritable.

My girlfriend thinks that I get so much sleep that I never really wake up, and there is a certain amount of truth in that. It does take me a few hours to wake up and do stuff properly once I'm out of bed, so I'd definitely be more productive if I could get by on less sleep. If I need to get work done I have to do it during the evenings when I'd much rather be doing other things.

My girlfriend likes to get up early and do stuff at the weekends, but if I get up on a Saturday at one or two in the afternoon and we want to see an exhibition or go to a market, then it's invariably closed by the time we get there. I want to change but if I don't get lots of sleep I just have a bad day, so it's a fine balance. I'd rather just have a short good day than a long crap one.

Interviews by Sarah Harris