John Shneerson, who is not a big man, sits in a large chair in a small room otherwise furnished by little more than a single bed, a sink, a series of wires and probes and a video camera. The dimensions of the chair reflect the girth of a good number of his patients, he remarks. Though by no means all of them. Sleep medicine isn’t that precise.

Yet as the presence of 3,000 new patients at his sleep clinic each year suggests, there is a growing demand for the help it can provide. Or rather, the demand has always been there, it is just that sleep medicine is a new and emerging science that is woefully underrecognised by NHS providers and GPs, as well as by the legions of people who do strange and sometimes dangerous things in their sleep. If you sleep badly your health could be at risk and you could be a danger to other people.

Get treatment if you have a sleep disorder — or learn to sleep properly if you don’t — and not only will you be happier and healthier, but so will the person who shares your bed.

Last week this point was made by new research which suggests that siestas cut the risk of heart disease. Shneerson, director of the sleep clinic at Papworth Hospital, Cambridge, has yet to be convinced of this but remains an advocate of the afternoon power nap.

“Fifteen to 20 minutes is enough to be refreshing without giving you grogginess afterwards,” he says. “Employers should make it possible for people to have short naps in their lunch hours in areas where it’s quiet. It would probably be cost effective and might well increase productivity because if people are less tired in the afternoons they make fewer mistakes and work faster. But it needs a change in culture so that it’s seen as the sensible thing to do.”

Shneerson’s mission is to increase aware-ness of the importance of good sleep, the existence of sleep disorders, and the ex- panding armoury of treatment available for them. He has even welcomed TV cameras to the clinic, and the BBC will report on some of the more bizarre patient histories from tonight.

But while Papworth is the largest sleep clinic in the UK, with six rooms equipped for monitoring sleeping patients and a £4m extension on the way, it is one of only a handful of NHS sleep facilities. Shneerson’s argument is that just as the public understands the benefits of exercise and a balanced diet, we need to recognise that sleeping properly is a form of preventative healthcare. So do GPs and those who educate doctors, he says.

“In the UK sleep medicine has only recently been recognised as a speciality. It’s now understood that the body functions quite differently during sleep, but sleep medicine has been very much neglected. Very few consultations take place when patients are asleep, and patients don’t have much to compare themselves with so it’s not easy to know that they’re doing something abnormal — and treatable.

“The average medical undergraduate teaching gives sleep medicine five minutes in five years. We need a more appropriate balance between resources for medical conditions occuring during wakefulness, and those occuring during the eight hours of sleep.”

In non-dream sleep, the muscles are paralysed or relaxed and the body runs on automatic reflexes, ticking over at a lower metabolic rate than during wakefulness. This allows the body to recover from the previous day’s activities, to get rid of chem- ical toxins, and to restore energy levels. The higher parts of the brain are switched off. In dream sleep there is more muscle activity, and brain activity is more chaotic, but the body is still driven by its own rhythms rather than by the environmental forces that control it during the day.

Thus sleep is restorative, and not getting enough carries penalties that often go unrecognised. How often when we moan to a GP should we be looking instead at whether we’re sleeping properly? That’s a fair point, Shneerson says.

“If you treat sleep disorders, you can prevent other medical complications. Sleep apnoea [which causes sufferers to stop breathing during sleep] is associated with an increased risk of heart attacks, strokes and high blood pressure and a six times greater risk of road traffic accidents. Between 10 and 20 per cent of fatal road traffic accidents on motorways involve a sleepy driver.

“Getting good sleep is important to the individual and to the economy. If you’re sleepy, you’re more likely to have accidents at work, people who have sleep problems have more time off sick, more unemployment, and they are more likely to fail to get promotion.”

Their relationships suffer too because they tend to be tense. “There’s certainly a lot of marital breakdown in people with sleep disorders, particularly for people who are physically restless, or who snore or have sleep apnoea.

“If you come home in the evening and fall asleep — what sort of a relationship is that? Your social activities are curtailed, or you don’t do sport, and then you get inactivity and obesity.

“For children, lack of sleep affects their concentration, their ability to perform to their potential, and their social confidence, because if they’re sleepy they don’t learn to relate to other children. Increasingly, children don’t get enough sleep.”

Shneerson blames texting, and the prevalence of televisions in bedrooms. “For adults, bedrooms should be for sleep and sex; for children, just for sleep — their bedrooms should be associated with falling asleep and being asleep, not with all sorts of exciting activities.”

For adults living in a 24/7 society the average amount of sleep is seven hours. You can maximise your wakefulness by ensuring that your lifestyle suits any tendency to function well early or late in the day, but don’t make the mistake of assuming that you can habitually compensate for sleep lost during the week by sleeping more at weekends, Shneerson cautions.

“A lot of people do this but it’s better to have the right amount each night, because if you deprive yourself during the week and catch up at the weekend you give your body clock a shock. After the weekend it’s just acclimatised, then on Monday it’s back to a different pattern. What you’re doing is giving yourself mini jet lag every weekend.”

Should sleep be prescribed? Shneerson laughs. “The importance of having enough sleep should be emphasised by doctors and other healthcare professionals,” he says.

“There’s a tendency to talk about what the patient is aware of, and people often don’t volunteer problems about sleep, either because they don’t know they have them or because they regard what happens in bed as rather private and personal.

“If you feel sleepy you have to have increased motivation and drive to keep alert and get on with things, which some people can’t do.

“Margaret Thatcher had long periods where she had four or five hours’ sleep a night, but she was highly motivated and compensated for it. A lot of people find that doesn’t work and have problems with relationships and driving.

“When people are relying on motivation to overcome sleep debt, in boring situations they lapse, particularly between 2pm and 4pm, and at night. That’s when most unexplained single-vehicle car crashes happen. They also become irritable, they lose their mental creativity and flexibility, and they don’t do physical things as well.”

So sleep debt always has to be repaid. Is there such a thing as sleep credit? Unfortunately not.

Sleep Clinic starts tonight on BBC One at 10.35pm

Top tips for a good night’s sleep

- Take the TV out of your bedroom

- Have a hot bath before you go to bed

- Stick to the same bed time each night

- If your bed is more than ten years old, consider a new one

- Avoid caffeine in the evening — and you may need to limit it earlier in the day

- Go to bed in time to ensure that get a full seven hours’ sleep

- Switch off your mobile phone when you go to bed

Who suffers what

- 5 per cent of the population are excessively sleepy

- 1-2 per cent of adult males have sleep apnoeas

- 10 per cent of the population have restless-leg syndrome

- 15-20 per cent suffer from insomnia

- 30 per cent of adult males snore more than their partners would like

When to go to your GP

- If you think you are getting enough sleep but regularly feel too sleepy to cope — or fall asleep — during a working day

- If you conk out when you get home from work

- If you fall asleep mid-conversation, or during meals

- If you injure yourself or your partner when you are asleep

- If there is unexplained damage to your home in the morning, or evidence of missing food

- If your partner is regularly disturbed by your sleep-talking, sleepwalking or restlessness

Oh God, he’s snoring again

There are hundreds of sleep disorders, from insomnia and snoring to the more acute and dramatic conditions referred to the clinic at Papworth. People walk, talk and shout in their sleep, they act out nightmares, they can be violent, kicking, punching, fighting. Night epilepsy, which can be controlled by drug treatment, does not affect patients during the day, but during sleep these patients are frenetic, highly charged, shouting, screaming and thrashing around in a state of intense fear.

What sleep-disorder patients tend to have in common is that they are unaware of what they do when they sleep. Shneerson knows of cases where people have been killed by sleepwalkers; others walk out of windows, fall down stairs, have sex, or eat — usually sloppily — all with no idea of what they are doing.

“Very often it’s the partner who notices something’s wrong,” Shneerson says.

The partner is also likely to be the one who suffers most. While the patient with broken sleep feels tired the next day, the partner who has spent every night she can remember listening to yelps and screams, and being kicked, is likely to be exhausted and angry, especially if her spouse denies having done anything untoward (partners who complain about a spouse’s sleep disorder are usually women).

The most common sleep disorder is restless-leg syndrome, which affects 10 per cent of the population, and 2 per cent to a troublesome degree, causing people to kick their legs in sleep: they may do this every 30 seconds.

Sleep apnoea causes people to stop breathing at night, though the patient is unaware that anything is wrong until he finds himself so sleepy during the day that he is unable to function properly — or until his partner complains about his excessive snorting. This condition affects between 1 and 2 per cent of the population, but 80 per cent of cases are untreated.

“Maybe 5 per cent of the adult males who snore more than their partner would like have significant sleep apnoeas,” Shneerson says. “The airway closes when you breathe in, so you can’t breathe. You snore loudly. Then you stop breathing, and after 20 or 30 seconds the brain doesn’t like being strangled so you wake up with a big loud snort and jolt and shake. Then the airway snaps open and you can breathe, and you fall asleep and do the same thing again. You can do that 500 or 600 times a night; each one wakes you up for a moment, so your sleep is so fragmented that you feel tired the next day. So you suffer — work, family, relationships — and you may kill yourself in a road accident.

“This condition is a risk factor like having high cholesterol, yet it’s not well recognised. With cholesterol there’s been a push to get everyone treatment. There’s no national push with sleep apnoeas. Health economics says why don’t we prevent these problems? The humane side says why not treat people whose quality of life isn’t as good as it could be.”

Treatment of sleep disorders may involve drugs, and weight loss is often recommended. “The nice thing is that if you treat one person you get two better,” Shneerson says. “If they’re both functioning the next day rather than tired, one feeling guilty and the other angry, they’ll have a better relationship. ”