For those who come from, to put it fashionably, dysfunctional families, Christmas can be a time when the strains in family life appear to be boldly marked out in highlighter pen, the hatred and jealousy hanging in streamers of resentment over the underdone turkey. Cracks that can be easily papered over during snatched family get togethers during the year now appear far more clearly.
The general stress of Christmas is designed to put a strain on even the happiest family, and women in particular. Present-buying, card-sending, lunch-organising, tree-decorating and stocking-filling nearly always fall to the woman, and though the actual Christmas dinner is one of the easiest in the world to cook (anyone who thinks otherwise should try making a Thai curry for six) it is the general hoo-ha that makes Christmas a trial for a woman, particularly if she's already spaced-out by working at a job. Added to this, it is the school holidays and the adult Christmas holiday itself can go on for at least two weeks; two weeks when a couple who may have only seen each other for fleeting moments through the past weeks if they're both working suddenly find themselves in each other's faces during a stressful time.
"If things have been swept under the carpet during the year, they come to the surface at Christmas," says Zelda West-Meads, a Relate counsellor whose book, The Trouble with You, (Hodder and Stoughton, pounds 6.99) is just out. "Another problem is that if you're having people to stay, you have two or three whole generations of people in the house with completely different needs. You're in between trying to please the older generation and trying to please the younger generation and if you're at each other's throat as a couple you wonder why Christmas can't be cancelled this year."
More than one television, organised walks,endless jigsaws for loners, and clearly defined chores for everyone can all help to make Christmas more bearable, entertaining even. And although no one wants to be forced to do things they don't want to do, there is nothing more scratchy-making than the feeling that there is nothing to do but drink.
"Establishing the time of arrival and time of departure in advance can take some of the stress out, too," says Ms West-Meads. "Three days is usually long enough, particularly as people feel trapped not only with not being able to drink and drive, but also because there is so little public transport."
It's worth, too, taking a little time to dash your expectations before they crash down your ears. So often we imagine a story-book family Christmas with everyone sitting round the table laughing, putting on paper hats, and loving each other. The expectation only highlights the problems in our family life despite the fact that nearly all normal families have feuds and difficult relatives.
A more stressful Christmas scenario is when you're on your own. As this is my first Christmas alone for about 20 years I know that it's important to accept every invitation on offer. Not only am I spending Christmas away, but I'm driving back to town on the day itself (to another invitation) giving myself three hours in the car, an excellent place to spend a lonely Christmas. On Boxing Day I take off for the sun.
Christmas in a stepfamily can be full of emotional pitfalls, too, particularly for the visiting child. Perhaps your stepmother doesn't understand about stockings, and uses pillowcases instead; perhaps the rituals are all quite different from the ones you know at home. "When I was with my father at Christmas," wrote the journalist Candida Crewe, recently, "I desperately missed my mother, and vice versa. Tearful telephone calls would ensue. One year I drew a chart with the day's hours and seconds to go before I could return to whichever parent it was that I wasn't pulling the crackers with."
If both parents want to see their children opening their presents they should try to organise a short Christmas truce which involves them smiling and joking in the same room. (Not something Charles and Diana have managed this year, sadly, a poor model for other separated parents.)
"If a child does spend Christmas in a stepfamily it's important that the traditions aren't entirely unfamiliar so that new traditions are forged in a new family. Children from both families should have a choice in how to celebrate Christmas," says Zelda West-Meads.
Another way to spend Christmas in a stepfamily is to spend it on territory that's completely new to everyone - perhaps a night at a hotel.
Finally, there's the guilty Christmas when you and your partner have decided to make a break from it all and spend it away on your own. It's possible to assuage the resentment at home by doing more than is expected of you. Two phone calls rather than one; perhaps neighbours could be persuaded to hide a large bunch of flowers which they could drop in at lunchtime to the family?
Christmas takes real emotional effort. But with that effort it can become at least tolerably happy, maybe, even, a time when lonely people can find company, modern confused families can reform, and the in-laws, the uncles and the aunts can put aside their differences and behave as if they love each other.