Christmas is for children.

And it's a safe bet that you -- dear grown-up, professional, competent reader -- are one of them.

Psychologists have long noted that when adult "kids" return to the family homestead for the holidays, they tend to revert to childhood patterns. No matter how long they have been living independently, put them back in the old bedroom with the Barbies and the track trophies and they once again assume the roles of dutiful little boy, rebellious daughter or pesky sibling they should have outgrown along with Santa.

Subsequently, depending on the family's dynamics, and its members' attitudes toward the holidays and each other, Christmas get-togethers can resemble either a heartwarming Hallmark special or one of the more hellish episodes of "The Simpsons."

"Certainly, the holidays have a way of bringing out the child in us, and that's very healthy," says Charles Maloy, director of the counseling center at Towson State University.

For Carolyn Brown, media relations director for Image Dynamics, getting together with her parents, four siblings and assorted pets for the holidays means silly presents, inside jokes and time-honored childishness.

"My sisters Pam and Ginger are twins," she says. "From the time they were in the playpen, someone would hand each of them a present at the same time, and they they would sit back to back and race to see who could open it first. They still do it -- they are twins to the end."

Dawn Bunyan, director of marketing for Eastpoint Mall, maintains the same kind of affectionate relationship with her sister and brother, now in their 20s, when they return to Boston for Christmas.

"Since he was a little boy, my brother has always gotten up early on Christmas morning, and gone to everybody's bedroom to wake them up," she remembers. "He would literally drag them downstairs to see what Santa had brought. He's 26 now, and is getting married next year, and he still does it!"

However, Dr. Maloy cautions, less rosy scenarios can result when family members cherish unrealistic expectations; expectations not only about the fabulous Christmases we see in magazines and the movies, but expectations about each other.

"The higher the expectations, the greater the probability that they are not going to be met," he says. "We all have scripts in our heads, and if these people don't fulfill the scripts, and play all the right parts, that's when conflicts develop. We have to have the willingness to let other people be themselves."

When parents and their adult children have unresolved conflicts about their roles, issues of power and control can bubble to the surface at any family gathering. But such issues are especially treacherous at Christmas, when emotions are heightened, and when there is considerable cultural pressure to be blissful, says Thomas Krajewski, public affairs chairman for the Maryland Psychiatric Society.

The situation is most severe for families torn by alcoholism, drug or mental problems or marital discord.

"I think the worse the family upbringing, the more bad memories and emotional triggers can occur," observes Harold Steinitz, coordinator of the stress management program at Sheppard Pratt Hospital. "People from dysfunctional families can become re-traumatized. They may fall back into old roles of caretaker, hero, scapegoat."

But even "normal" families run into trouble when parent and child, or siblings can't see each other as grown-ups and peers, says Anthony Di Cesare, a Towson State psychology professor and psychotherapist.

"Kids leave the nest, they become adults, and then when they go back home, especially at a holiday, they're almost required to become children again," Dr. Di Cesare says.

Conflict, he says, crops up when parents, unable to cope with a grown child's autonomous lifestyle and possibly differing values, attempts to regress him or her to an age of pliant dependency.

"When the kids were 5, or 6 at most, [the parents] had control over the situation. they could give the child virtually anything, and the kid would be happy," he points out.

Lingering tensions between family members, including sibling rivalries, often result in a habit Dr. Di Cesare calls "gunnysacking."

"You take all these old wounds and old complaints and throw them in the sack," he explains. "On Christmas you want to empty the sack in the middle of the floor. But unlike Santa's sack, it's not full of nice presents!"

He advocates defusing such situations by acknowledging the complainer has a reason to be angry, but calmly explaining past misdeeds can't be undone. Then ask for suggestions on how the relationship can be improved.

Talking out family disputes can be profitable, agrees Dr. Krajewski, but is often better done after Christmas, when feelings aren't running at such a high pitch.

"After the holidays, sit down and discuss your conflicts," he says. "Resolve to start anew. In fact, I think that's where the tradition of New Year's resolutions came from."

Too much "togetherness" is a frequent cause of holiday irritability, Dr. Steinitz says; somewhat aloof families may feel pressured into an uncomfortable state of intimacy, and close, "enmeshed" families may have difficulty realizing the need for emotional and physical space.

"We need to regulate space and closeness," he says. "My family is from out of state, and when we get together, we limit it to five days at a time. We have mornings off, then spend afternoons together, because you need some solitude even when you're visiting."

John Blakely, a psychotherapist in White Marsh, suggests taking walks with individual family members to lay the foundation for greater emotional closeness. It's hard to stick someone in the role of "annoying little brother" or "mean old aunt" when you learn to know the person, adult-to-adult.

The secret to surviving the holidays happily, Mr. Blakely says, is to find new ways to make them meaningful, whether it's spending more time with people whom you enjoy, or helping at a soup kitchen.

"I think people need to take charge, make Christmas feel good to them," he says. "If they create some rituals they like, they can create new memories for next Christmas."

"People need to go out of their way to replace painful rituals with new ones," agrees Harold Steinitz. "There's a guy I know, who came from a pretty dysfunctional family, who goes out with his family and buys bags of groceries, and drops them off at a shelter. His own small family does this together as a healthy way of sharing."

And if your Christmas is still not Hallmark-perfect? Don't sweat it.

"People think, "Because I'm not joyous there's something wrong with the way I'm feeling,'" John Blakely says. "But it's OK to have mixed feelings about Christmas."

How to survive the family get-together

Here are a few suggestions on how to have a sane, as-happy-as-possible family holiday:

* Keep your expectations reasonable. "Typically, at the holidays, people have a certain standard for a happy holiday: 'It should be like what you have on television, the Hollywood ideal,' " Thomas Krajewski says. But, remember, your family didn't come from Central Casting, and don't expect perfection from them -- or yourself.

* Avoid role-playing. Parents, remember that your "children" are adults, and keep meddling to a minimum. And "kids," don't reinforce old roles by acting childish. No whining, squabbling, and making Mom wait on and clean up after you.

vTC * Schedule some personal time. "There's a natural need for space on a regular basis," says Harold Steinitz, coordinator of the stress management program at Sheppard Pratt Hospital. So don't overdose on togetherness. Take a walk, visit old friends, go to the art museum.

* Take it easy. Forgive your family their imperfections, and don't get upset over trifles. "You know you're only going to be there for a short period of time," says Anthony Di Cesare, a Towson State psychology professor and psychotherapist.

* Think of some alternatives to going home, if your family situation isn't salvageable. "I have a patient who decided this Thanksgiving not to go home," says Dr. Steinitz. "She was saddened, but it strengthened her." Members of dysfunctional families can make future Christmases happy by forging new traditions, such as spending time with friends, taking a vacation or helping the needy.