Far from being stressful, this is a time when we can really relax. And happy people are healthy people, says ROGER DOBSON     (Sunday Times)
Christmas is a happy time, really it is. Mentally, socially and even physically, it's the healthiest few days of the year. People talk to each other more, enjoy giving presents and thrive on a visit to church. Happiness boosts their immune systems, work stress disappears, feuds with family and neighbours get healed, more nutritious food is eaten, midwinter blues are blown away and we laugh more than at any other time.
By the end of it all, we are so invigorated and full of optimism that new year's resolutions are made, usually centred on health and lifestyle, in the hope that improvements will make the rest of the year as good as Christmas.
Despite all that happiness, Christmas has become bogged down in the now traditional doom and gloom reports of higher seasonal rates for almost anything that's bad, from depression, suicide and murder, to family squabbling, divorce and obesity.
Precisely why we focus so much on the bad things is not clear but, according to Professor David Myers, of Hope College, Michigan, who has spent years in the academic pursuit of happiness, one of the problems is that his fellow academics and psychologists are so obsessed with investigating depression and stress that joy barely gets a look in.
Myers's investigations into his colleagues' predilections for the gloomy side of life established that, over the past 17 years, there have been nearly 80,000 research projects on depression and anxiety and only 2,389 on happiness and a modest 400 on joy.
But despite the gloomy reports, many based on myths and misunderstood statistics, research shows that happiness - or "subjective wellbeing", as psychologists prefer - is at its peak at Christmas.
Primarily, says Dr Lance Workman of the University of Glamorgan, it is a time for bonding: "It is the most important festival of the year for many people and the normal rules of everyday life are relaxed. It allows people who have argued or not spoken for months to put that aside without losing face. We also make more of an effort to meet people and that makes us feel good."
Although the number of couples seeking divorce does peak after Christmas, as it does again after summer holidays, it is argued that many of those relationships are already on the rocks before the couples are forced to spend time together. The happiness of others proves to be the final straw.
A lot of that wellbeing comes from the act of giving at Christmas. Giving is a kind of mental colonic-irrigation exercise, removing low self-esteem and making us feel healthier, happier and more comfortable with ourselves.
But, warns Workman, it only works if you obey the two cardinal rules: never give an inappropriately expensive present because it may be taken the wrong way and never give money unless it is to someone younger within the family.
Another tonic for the mind at Christmas is religion. Even if it is a once-a-year experience, it bonds us into a community where there is greater social support, optimism and hope. One Gallup survey found that those who attend church are twice as happy as those who don't.
Other organised family events, such as Boxing Day sports, help to make us feel part of the group. Even visits to relatives, also an integral part of the festival, help to bind families together in the long term, even if there are short-term stresses and strains.
Because of the modern pace of life, we also need Christmas for our health and welfare, says Professor Cary Cooper, a psychologist at Manchester university.
"Christmas has become so important, probably more than ever before. We have the longest working hours in Europe, and we have a lot of stress-related problems. Christmas is a respite from all that.
"Two out of every three couples are now working couples and that makes life frenetic: forget quality time, we are not having any time at all. That makes Christmas a good time for communication between parents and families and children," he says.
Being happy is good, too, for our physical health. Latest research shows that the killer cells in our bodies that attack viruses and other invaders get suppressed when under chronic pressure - and when people are happy the immune system functions much more effectively.
According to research in the US, happy people, as measured by the number of close friends they have, rather than the number of Christmas cards they send, are more healthy and less likely to suffer a premature death than loners.
Christmas is also a time of moderate drinking for most people - and research shows that moderate drinkers laugh more frequently than either teetotallers or heavy drinkers.
According to psychologists, happiness can be measured by a number of factors. While depressed people are frequently inward- looking and hostile, happy people are usually optimistic, gregarious and extroverted. They will believe they are more intelligent, more social and healthier than other people, will have higher levels of self-esteem and will believe they have a high degree of control over their lives.
The trouble with studying happiness, though, is that many people always say they are happy, because admitting to being unhappy would make them feel a failure. In surveys, for example, less than 10% of the population will admit to being unhappy some of the time.
Nevertheless, recent research shows there has been a decline in the number of people who are happy, and over the past three decades the proportion of people saying they are very happy dropped from 35% to 29%.
Surprisingly, Myers' research shows that levels of happiness appear only marginally affected by factors such as age, race and social status. He reports that even the 100 richest people in the world are only slightly happier than those of us struggling to pay the mortgage or making do with a fortnight in Margate, which means, for most of us, there really is no excuse for being miserable this Christmas.
For those still not convinced and dreading the seasonal festivities, Dr Jill Wilkinson, a psychologist at Surrey university, has 10 tips for a happier Christmas:
Dare to be different: family routines and rituals get boring. Think up new ways of doing things.
Negotiate: include all the family in decision- making about Christmas.
Sort out priorities: identify the conflicting demands from within the family.
Be realistic about expectations: it avoids disappointments and thinking positively helps to keep you cheerful.
Spread the load: buy gifts throughout the year.
Avoid deadlines: stop using Christmas as the time limit for decorating the living room.
Face saving: make allowances for changing presents at the last minute when the intended recipient gives you a better-than-expected gift.
Avoid radical changes: remember, the gastrointestinal system that is accustomed to eating prawn sandwiches at lunchtime might get overburdened by a huge roast dinner.
Look after yourself: bad-tempered, frazzled folk make for an unhappy Christmas.
Escape: if all else fails, try the Maldives.