It's meant to be the season of goodwill and peace on earth but it doesn't always work out quite like that. Whether it's irritable toddlers, harassed parents or grown-up children returning to the bosom of the family home, demanding that things are done their way, the potential for strife is great and the usual overindulgence in food and drink does nothing to soothe frayed tempers.

Psychologist David Coleman cites a number of reasons for family bust-ups at this time of year.

One is that parents are often under big financial pressure. They may have issues with their own extended families and the thoughts of gathering together for Christmas heightens their own worry and stress. He also points out that it is a very busy time, and that can add to the pressure.

"When parents are under pressure, they are less likely to be consistent in responding to their children and less likely to cope with their children's misbehaviour and anything that goes wrong in the family."

Children, depending on their age, tend to have huge expectations coming up to Christmas.

Parents often struggle with managing those expectations, particularly if they know that Santa Claus isn't going to be able to provide everything that's asked for.

"When children get disappointed they show that behaviour by acting their disappointment out instead of dealing with it differently. And then you've got a whole change in routine. Routine is thrown out the window for Christmas and everybody tends to be up later so they're more tired as well and when children get tired, they get cranky."

Christmas, he says, is a time where we have an expectation that families will come together but often families are apart for good reasons . . . because people don't get on.

"We often try to force ourselves to get on with people over Christmas when in fact that's not actually possible and so because somebody decides to host a family gathering, everyone is expected to be there but it just brings old tensions to the surface."

Throw in teenage moods to the melange and you've got another potential for disharmony. Coleman says: "They're going to be hanging around with their families so much over Christmas and this can often be a bone of contention. Teenagers are used to having more time to themselves and being out with their own mates. Suddenly, they're expected to go along to different family gatherings and hang out at home and that can cause tension too."

Tips for a peaceful Christmas

Parents need to do look after themselves over the Christmas period and not indulge in too much drinking, which increases stress and doesn't reduce it.

Get out and get some exercise and away from the preparations so you don't feel overwhelmed.

Reduce the number of activities and schedule some downtime.

Manage your children's expectations. Talk to them about how they will cope if Santa Claus can't give them what they asked for.

This will help them develop a coping strategy for any disappointment.

Structure children's time.

Younger children particularly need things to be organised and when they have a lot of unstructured time it increases the likelihood of sibling rivalry and rows.