Q. "I'm resurrecting a letter I started to send last year, when as usual, Christmas Day turned into chaos.

"For some reason the rivalry between my two boys (11 and 13) often turns into general cussedness, anger, tears, and sometimes bedlam on special days. And since Christmas is the most special day of all in our family, their behavior goes to pot at least once during the day.

"I don't see why they can't be happy together. One child is an extrovert, one an introvert, but my husband and I are like that and we get along.

"Since 'm sure this Christmas will be no different, can you suggest anything to keep the peace? (And the weeks afterward, for that matter.)"

A. The more people look forward to an event, the bigger the letdown is likely to be -- and children look forward a lot.

Some problems can be forestalled.

A lot of chaos is caused by sugar. It bothers many children, particularly when it's eaten on an empty stomach. There is so much candy about at Christmas that no sensible child is going to make a proper breakfast and lunch, and you're probably much too busy making dinner to do it for them. Instead, push tangerine, nuts, apples with cheese or apple slices smeared with peanut butter. The fewer sweets a child eats and the fewer carbohydrates -- manufactured ones, that is -- the better he will behave and the healthier he will be.

Time also can be a troublemaker today. Since Christmas starts so early with children in the house, they must be programmed gently -- or not so gently -- to make the extra hours go smoothly.

Some of the time is spent going from house to house, comparing presents with their friends, but there will be many hours left. And if you expect your boys (or any boys, or any girls) to spend the time playing quietly together, you're living, as our children would say, in F.P (as in Fool's Paradise).

You're looking at a couple of springs about to get unsprung. You only can hope they will unwind slowly enough to keep from flying apart.

See that they get peace and quiet for an hour or so, to balance all the excitement they've had, which only will happen if your sons go to separate rooms. This is a good time to read their new books and relax (and let you relax). Insist upon it, and before there is a scene.

Your children also need some exercise today, either before or after dinner. A neighborhood game of soccer is great -- nothing gets rid of agression so nicely -- or some bike-riding or running or sledding, depending on the weather. Here the boys can play together, but each in his own space, so their tempers don't collide.

It's even better if you or your husband can join them, if only for a half-hour. When parents take part in their children's games it shows respect, by recognizing that their pastimes are important, too. Your reward may be slow in coming, but respect is always repaid to the exact degree that it is given. And when it is, your children will be more willing to take part in the activities you like.

The more common ground you can find, the happier the family will be. Sometimes the pleasures are at your level, but this week they're usually at theirs. Now you learn their new games -- perhaps even the marvelous Dungeons and Dragons if you dare, although you may have to be 12 and 14 to be so chancy. There can be a few wild rounds of Pig, or some hours of Monopoly or charades. A family is to enjoy; that's why you had children.

Work is shared this week, as always, but don't expect much from these wrung-out souls. Even though it's limited to tidying up, it won't be done unless you do it with them. This is not a week to nag. It never does much good anyway, but it does less now, so you may as well give it up as your Christmas bonus to them.

There will be less tidying necessary if you get out of the house a lot: the way you did when they were 2.

There can be good family missions to the museums, but since it seems like almost everyone in the metropolitan area visits them after Christmas, it's best to take the subway to the Smithsonian. For a classy trip, get on the Tourmobile. It's an adventure in itself, and since you can get on and off all day, it's much easier to go to everyone's favorite building.

Consider your own peace of mind and send the children out alone. The movies are great -- and don't hesitate to let them go to separate movies, or on different days, for they need to be apart.

Help them set up some overnights, for the same reason. When one child has a friend over and the other sleeps out, they each feel good about it. And when one child goes out, you have the chance to strengthen your bond with the one who stays home.

With any luck at all, there should be one night when they both sleep out.

Parents deserve a holiday, too.