Could you be suffering from 'social jet lag'?

If you spend most of your life feeling like you've just stepped off a long-haul flight, you could be suffering from 'social jet lag'. Kate Hilpern reports

It might be the middle of the day and I might be drowning in paperwork, but sometimes it's all I can do to resist sneaking forty winks into my afternoon routine. I'm not alone, it seems. More than half the population is in a permanent state of jet lag because our body clocks are so out of synch with the demands of modern life, and a new study has pinpointed some disturbing consequences of the condition.

"Social jet lag", a term coined by the researchers, can hit you even if your commute is more akin to travelling from Lewisham to Leicester Square than from Stansted to the States. But the effect is the same because your body clock is screaming one thing (that you should be in bed, for example) whereas the outside world says something else (that you should be in a meeting or getting the kids to school).

"Getting up in the morning and going to bed at night is not just a pure reaction to sunset and sunrise," explains Professor Till Roenneberg, who headed up the team of researchers at Ludwig-Maximilians University in Munich. "It's also down to your genes, which can determine how much of a night owl or early bird you are."

The distribution of owls and larks across the population is huge, he says, with a spread of more than 12 hours between people's natural rhythms. This means that if left to their own devices, the first lark would bounce out of bed well before the last owl nods off. This, of course, doesn't fit comfortably with most work routines, with the inevitable result that a lot of people wind up feeling fatigued.

Add to this the fact that we're working longer hours than ever and you'll see why social jet lag affects more than 50 per cent of us - especially when you learn that people who are stuck inside an office during daylight hours are the worst affected. "Bright light can help shift even the most extreme body clocks," says Professor Roenneberg. "But the amount of light in most offices is laughable. You would be lucky to get 400 lux [a unit of measurement of the intensity of light] at a bright vertical office window during the day, whereas outside on a cloudy day in summer you would experience more like 10,000 lux. If it's a blue sky, you could get as much as 150,000 lux."

For night owls, this is particularly bad news. The most natural response is to race out of work to enjoy the last of the sunlight, which only serves to reinforce the late body clock and make them feel groggy again the next morning.

Most worrying of all is that general tiredness is just the tip of the iceberg when it comes to the effects of social jet lag. "Your daytime vigilance is lower, which means that if you work, you may not focus on your job properly," says Professor Roenneberg. "We also found that people with social jet lag sleep more poorly and are more prone to suffering from stress and depression."

Then there's the impact on physical health. Indeed, actual jet lag - which has the same affect on the body - increases the risk of cardiovascular disease, certain cancers and other conditions. The British Dietetic Association adds that tiredness commonly leads to laziness about eating healthily. A spokesperson says: "Some people who are tired crave certain foods like fat or sugar, while others don't feel like eating at all. The outcome of any of these behaviours is that your body isn't getting the nutrition it needs to function at its best and you are also more prone to illness."

Professor Roenneberg's study even found that social jet lag can drive people to smoke. Seventy per cent of the night owls in the study were smokers, compared to just 10 per cent of people whose working lives fitted with their body clocks. These people tend to opt - usually subconsciously - for the stimulant effect of cigarettes just to get through the day, which carries a whole host of additional health risks.

"You could argue that night owls are more likely to smoke because they like being up until late and are therefore more likely to be in places like pubs and clubs, where smoking is commonplace," he says. "But if that were the case, you'd expect people who stay up late to smoke more than smokers who don't have problems with sleep timing. That is not the case. We can only conclude that people with social jet lag use smoking as self-medication," he says.

The study also claims to provide enlightenment on why most people take up smoking in their teens. "It's no coincidence that most people start smoking between 14 and 20 years old, when the body clock is at its latest ever," he says.

Throughout childhood and adolescence, he explains, the time we head for the bedroom, and get up in the morning, shifts to later, peaking at around age 20 before it starts creeping back again. By the time you've hit your twilight years and traded in your blond bob for a blue rinse, you're likely to prefer getting up as early as you did when you were a young child. "I'm not saying social jet lag is the only reason people take up smoking," says Professor Roenneberg. "There are clearly other issues like peer pressure and genetics. But if you suffer from social jet lag, you are probably more prone to become a smoker, and if you continue to suffer from social jet lag, you are probably going to find it harder to quit."

Professor Dirk-Jan Dijk, director of the Surrey Sleep Research Centre, agrees. "We already know that shift workers - who desynchronise their sleeping patterns more than anyone - smoke more than the average population, so these new findings make absolute sense," he says.

He also agrees with Professor Roenneberg that there may be a solution to social jet lag. "There is something to be said for the idea that making school schedules fit in with adolescents' natural rhythms would make youngsters more productive," he says.

Likewise, making work schedules more flexible could enable bosses to get more out of their employees. Some employers have already taken action by encouraging staff to take catnaps in a "ready bed" (a roll-up bed specially designed for use in the office) which is generally placed in a darkened corner of a meeting room. Meanwhile, a dedicated sleeping lounge has just opened at the top of the Empire State Building in New York to enable executives to catch up on some shut-eye during the working day.

But Professor Dijk believes such attempts are misguided when it comes to tackling social jet lag. Taking a nap can help, but there's as much chance that it will make you feel worse. The key for employers, he believes, is to make working hours more flexible overall so that people can have their main sleep when it best suits their body clock.

Hopeful larks and owls may have a long wait, however, particularly if their bosses concede to Jim Horne's views on the subject. The sleep expert from Loughborough University isn't convinced social jet lag even exists. "Yes, some people are more inclined to be alert in the evenings and others in the mornings. But to suggest that there is something wrong with them - that they are jet lagged - seems absurd," he says.

In fact, there are advantages to their state, he says. "Think of the expression, 'the early bird catches the worm'. Morning types up at the crack of dawn may get the best opportunities in terms of work. Meanwhile, owls who tend to go to bed later may be better socialisers because most social activities happen in the evenings."

The symptoms

Do you: Long for a lie-in - or have a lie-in - of several hours every weekend?

Regularly turn to the stimulants of cigarettes, coffee etc just to keep you functioning during the day?

Find yourself regularly wanting to go to bed much earlier or later than other people you know, and often feel "out of synch" with the world?

Frequently dream of having a siesta - and sometimes take the opportunity to take a nap during the day?

Feel groggy most mornings when you get to work and take a long time to "get going"?

How to beat social jet lag

Retrain your body clock: If you're a night owl, go for a morning walk, and wear sunglasses after 4pm. Conversely, early birds should make the most of the sunlight lasting later into the evenings.

Get into a regular sleeping pattern: Night owls who make the most of lying in for a few extra hours at weekends will delay their body clock and wind up feeling groggy on Monday and Tuesday.

Avoid stimulants: Don't drink caffeine or alcohol before bed, and while exercise will help you sleep, make sure you're finished three hours before bedtime.

Don't smoke: Smoking can interfere with our sleeping patterns. So while you might smoke to keep yourself awake you'll actually worsen your social jet lag.

Get a job that suits your rhythms: Larks make great postal workers, while working in a nightclub will suit serious owls. Or, convince your boss that you'll work more productively around your natural sleeping patterns.

Sleep well: Dr Adrian Williams, who runs the sleep centre at St Thomas' Hospital in London, says: "We are a sleep-deprived society. The average amount of sleep needed by adults is 8.1 hours, yet most of us only get around seven."

Use light therapy: If natural light is hard to come by, £100 can buy a mobile source.