STEVE Kelly is on his day off, which, for many other 22-year-olds, would mean crawling out of bed some time in the afternoon and spending the rest of the day seeing off a hangover. Kelly feels and looks fine, though. He doesn't drink, take drugs or have promiscuous sex. Being straight edge, he explains as he gently prods a teabag in a Glasgow coffee shop, means always waking up with a clear head. He doesn't remember what a hangover feels like.

Straight edge is referred to as a philosophy or a state of mind, but the movement has evolved more as a practical solution to a problem affecting a small group of people.

It has no particular political slant and, while it recruits and functions as some fringe faiths do, it has no god, no authoritative text and no single founder.

It is simply a set of rules which some, such as Kelly - articulate and mild-mannered - follow quietly and others are more vocal about. Indeed, many other followers in the area would sooner people don't really find out much about it, angry that many contemporaries and some commentators have little sympathy for straight edge's rigid basis.

Straight edge - often written as sXe - began in the early 1980s in Washington DC, where a number of groups in the punk-rock scene grew sick and tired of older, drunk people turning up to their shows and causing fights. The concerts would be stopped and the bands, not the fans, prohibited from playing the venues.

Minor Threat, fronted by Ian MacKaye, were the first group to take the idea to an almost evangelical level.

The alternative music scene that developed from there provides straight edge with its momentum and has allowed it to travel continents. Because it has no real membership, it is difficult to say how strong the movement is in Scotland, although it appears to be buoyant and most appealing to those in their late teens and early twenties. Kelly has a loyal circle of like-minded friends based in Glasgow.

Some are attracted to straight edge after an accumulation of bad experiences with drink, drugs or unfaithful partners. Kelly saw it as basic common sense.

"Having something positive to look forward to and work on; a general feeling of wellbeing, being part of something - that was the appeal. You find that people who lead this lifestyle are really positive people. You'll rarely find an unhappy or depressed person who lives like this, " he says.

Kelly stopped drinking and taking drugs at about 16, before he had even heard of the movement. "The big one that really opened my eyes to being straight edge was playing in a band. The whole rock-and-roll lifestyle is drink until you fall [over], sleep with as many women as possible, do drugs. Because one of the members of the band had been straight edge for 10 years, I got to know about the whole lifestyle and saw it made sense.

"To abandon the old circle of friends was hard, because these people were my best friends. To see them get into that state and not care was heartbreaking."

In Scotland, straight edgers, for obvious reasons, tend to regard abstinence from alcohol as the most important element of their clean living. "For some people, drinking does work, " Kelly concedes. "They are happy, they have a drink, but there are some who use it as an escape, to deal with their problems without actually dealing with them. I feel the way I deal with things is head on. I wouldn't pussyfoot around."

Kelly is saddened by Scotland's binge-drinking culture. He trained to be a nurse for a year, but eventually had to give up.

"People on the course were a lot more interested in going out and getting drunk than they were in learning anything about nursing.

One of our biggest exports is whisky. For a Scottish person not to drink is unheard of, " he says.

Having such conspicuous habits, for Kelly, can't be defined as a rebellion as such. If he was going to rebel, he'd just have drunk much more than his parents and made a big nuisance of himself. When he turned 18, however, he was ridiculed by friends and family for not drinking at his joint birthday party with his cousin.

"My parents both drink. They probably respect [my choice] more now, because it's been a really long time since I had a drink and I suppose I've saved them some hassle, " he says.

Other straight edgers, perhaps more in tune with the angry young men who originally fuelled the movement, see their lifestyle as a true rage against conventional lifestyles.

"Hardline straight edge has no tolerance whatsoever, even for alcohol being sold, " Kelly explains.

"Hardliners can want prohibition.

It's more common for people to have simply given up on the idea of being drunk at weekends."

He accepts that it is possible to drink in moderation, but strongly distrusts the false confidence of a few beers and abstains altogether.

"Some straight edgers are quite arrogant and militant, and do have a genuine hatred for anyone who drinks, takes drugs or sleeps around. For drugs and sleeping around, I have absolutely no tolerance whatsoever.

"Drinking I can deal with to a certain extent, so long as it doesn't affect me."

Even moderate straight edgers can attach personal regulations such as vegetarianism or veganism to the core rules of the lifestyle.

Kelly, a vegetarian, accepts that forbidding things can make them seem more attractive, but was so convinced this was a betterway to live that it was only pressure from friends, and not the temptation to drink, that made it difficult at first.

"The early stage was really hard.

If you didn't drink, you were classed as being gay.

"For someone at that age, it was quite a big step. It is a lot harder for somebody of that age to say no, " he says.

Having other friends who feel the same way helps, and the liveand-let-live nature of the youth tribal system means that straight edgers tend to feel neither isolated nor threatened.

As yet, Kelly has no giveaway "XXX" tattoo and doesn't volunteer his opinions on alcohol to strangers.

"If people are genuinely interested, then I talk, " he says. "If it's a case of someone just demanding to know why I'm not drinking, then I won't bother and just say it's my choice. You usually find it's students who ask, but don't get it."

All in all, Kelly feels the benefits have far outweighed the difficulties.

One night stands are a no-no, which to him just means cutting out a great deal of unnecessary emotional trauma.

Straight edgers tend to go out with their own kind but, as is the case with Kelly, whose girlfriend became straight edge after they started going out together, it can be seen as one of their attractive features.

"It does make you more reliable.

You don't come into work hungover. With partners, you have that reassurance that you're not going to cheat on them when you're drunk, " he says.

Common criticisms of the movement are that it can become slavish and that adherents end up being obsessed with narrow regulations instead of being guided by a more general sense of morality.

Kelly doesn't see himself changing his mind about his lifestyle when he's older, but seems to accept he might not always feel the need to label himself so clearly as straight edge as his habits become ingrained.

For now, the only restriction that bothers him is not being able to go to McDonald's with his friends, but, he admits, he's really not that fussed about it, either.

STRAIGHT EDGE - THE FACTS

The term straight edge was coined by Ian MacKaye, the lead singer of US hardcore band Minor Threat, who shunned the nihilism of punk rock and promoted clean-living - no mind-altering substances and no promiscuous sex Two decades later, many straight edgers are also vegetarian and have moved the focus away from personal lifestyle choice to become more politically aware and active The rules are interpreted with varying strictness. Hardline straight edgers are intolerant of the sale of alcohol altogether The original "don't drink/ don't smoke/ don't f***" mantra is often misunderstood to mean that a straight edger abstains from sex. Within the context of a committed relationship, however, it is not frowned upon.