Sleep - who needs it?

WE'VE all experienced the results of having insufficient sleep - our eyes feel heavy, our normal functions are impaired and if it goes on for too long, we even start to feel quite ill. In fact, as experts have discovered, just 17 hours of constant wakefulness can cause significant effects, our brains being dulled in the same way as if we'd drunk two glasses of wine.

Yet how much sleep do people need - and does a longer spell in bed improve performance through the day? It seems that everyone is different, and while the optimum for most is 7.75 hours of rest, some have 11 every night while others only manage five. What science doesn't quite explain is just what benefit sleep brings - while it's essential to maintaining normal skills like speech and memory, it doesn't really seem to offer any real recuperation (an eight-hour stretch beneath the duvet saves only 50kCal, about the same amount of energy as a piece of toast contains).

Perhaps the simplest rule of thumb is to be guided by Jim Horne, who's based at Loughborough University and is an expert sleep researcher. "The amount of sleep we require is what we need not to be sleepy in the daytime," he says succinctly.

Though you would hardly think it likely given how much sleep she gets, Marie Green fits in with this philosophy. The 52-year-old head teacher, who is in charge at Polam Hall, a busy school in central Darlington, survives on less than four hours' rest. As she explains quite matter-of-factly, it's just a habit she's acquired.

"It doesn't vary very much and it's pretty close to three and a half hours," she says. "My pattern is that I normally go to bed at around about one o'clock and then I read, and I usually turn off the light at about quarter past, half past two. The alarm goes off at 5.45am but I don't need it - I'm always awake before it and I get up then. Basically I'm ready to go and I suppose it's like most things in life, it's a habit really."

While most people would find this amount of sleep completely insufficient, Marie maintains that she is fine and doesn't suffer ill effects. She will admit that she gets weary - but no more so than other people. "I think I experience tiredness in a completely normal way," she says. "I've become more of a morning person - I used to be really awake late at night and into the small hours and although I never sleep very differently, I wouldn't have regarded myself as at my sharpest in the very early morning. Now these are the hours when I do my most serious work."

The big advantage she can claim is having much more time to play with. She's learned to exercise restraint on how much work she does at home, although by anybody's standards, hers is not an easy job.

"I tend to work from between 8am and 8.30am and technically I leave between 6.30pm and 7pm, but here we run an extended day," says Marie, who lives in Darlington. "The normal school day ends at 4pm but there's a whole range of activities going on until 6pm and, of course, we have boarders, so the school never really closes. What I've learned over time is not to fill all the hours I'm awake with work, because that way I get very tired."

So just what does Marie get up to in the extra hours she has - would she not rather be asleep and is her wakefulness a nuisance? She claims there's plenty she can do and that it's really not an issue.

"I've never regarded it as a problem, I've always regarded it as a benefit, and I think if you're relaxed about it, you don't feel stressed," she says. "I think when people are insomniacs it's that agony of wanting to be asleep but I would only describe it as insomnia if I wanted to be different, so I absolutely don't think of myself as an insomniac. I just think of myself as someone whose body doesn't need as much sleep as someone whose body is average."

Apart from catching up with work, Marie spends many hours reading. Her book collection is immense and what she reads is very varied. "When I moved house I had just over 30,000 books and the removal people found it a real strain," she recalls. "They do kind of take over my house - I'm a real bibliophile. I read a lot of lighter fiction as well as thrillers, poetry and philosophy, and I'm an avid reader of detective stories."

There is another useful perk to not requiring much sleep - when she is travelling overseas, Marie escapes the dreaded jetlag, and though this does mean that she's awake while others snooze their way through flights, she does appreciate the outcome. "Overseas travel and jet lag are just not an issue," she says. "That, to me, is such a blessing."

It is impossible to say what makes Marie so very different but she has always been that way - she's never been an eight hour sleeper. She thinks her genes may play a part and just accepts it as her make-up. "My father worked shifts and had a changing sleep pattern but he didn't really sleep very much, so whether there's a genetic aspect to it I wouldn't know - but it strikes me as a possibility," she says. "I think it does interest people but I don't see myself as a subject for scientific research - I'm too busy!"

Tips on dropping off

For those who struggle to get to sleep, the following advice has been provided by the Sleep Research Centre in Loughborough:

1. No caffeinated coffee and minimal tea in the evenings. There is no harm in a little alcohol if it is relaxing and enjoyable, but it must not be taken with sleeping tablets.

2. Adopt a relaxing and fairly mundane pre-bedtime routine.

3. It is pointless going to bed until you feel sleepy. Ignore the clock - time is the insomniac's curse.

4. Remove from the bedroom all methods for encouraging wakefulness, such as the TV, radio and tea-making facilities. Only one book or magazine by the bedside.

5. Don't languish in bed trying to sleep. If you can't drop off within a short while after 'lights out', then abandon the bedroom and retreat to the sitting room, kitchen, or any other room associated with wakefulness. Avoid looking at TV or stimulating reading. Do something absorbing and distracting (nothing to do with work), ideally involving the eyes and hands. Perhaps do a jigsaw, make models.

6. Set the alarm and get up at the same time every morning, irrespective of whatever time you eventually fell asleep that night. This constant rising time is essential as it helps to reset the body's own natural clock that regulates sleep and wakefulness.