Many parents become concerned when they notice their children start to suck their thumbs, bite their nails or twirl their hair, fearing the innocent act will become a hard-to-break habit.
But experts say parents need not be troubled unless such behaviors become a reflex act for the way a child responds to stress.
These acts might begin by accident, such as an infant finding a thumb to suck on, and then continue because it is pleasurable or comforting. Later, without so much as a sideways glance from their parents, many will stop in their own time.
But children who still suck their thumbs in first grade or still bite their nails or twirl their hair well into elementary school may require some gentle encouragement to give it up.
"Kids are under a lot more pressure today than in the past, so we see a lot of these habit disorders," said David Elkind, a professor of child study at Tufts University in Boston and author of "Ties That Stress: The New Family Imbalance" (Harvard University Press, 1994).
"We have to realize it's not something children are doing to be nasty or mean or to embarrass parents, but it's a way they have of reducing stress," Elkind added.
Experts recommend that parents of children with extreme habits--those whose thumb-sucking is damaging teeth, nail-biting is causing bleeding or hair-twirling is causing bald spots--consult with a health-care professional for aggressive measures.
But for those whose children's milder habits persist, they offer these suggestions:
* Reduce stress in the child's life. Experts agree the first step for parents is to review the youngster's schedule and home environment for anxiety.
"Some kids are programmed too heavily, for example doing too many things after school. If they have too many commitments, then they start pulling their hair or biting their nails," Elkind said.
Children are also affected by home stresses such as conflict between parents and economic worries--as well as world news.
Elkind suggests that parents "look at the child's situation and see whether there is something in the child's life you could change."
* Talk with the child. A sympathetic approach is more effective than putting the youngster down for, say, chewing on his nails. Explain to the child that his way of reducing anxieties has become a habit. An understanding parent will be more likely to gain the child's cooperation in exploring ways to break the habit.
But continually reminding the child every time he puts his hand to his mouth may backfire.
"When you make a big deal, it tends to exacerbate the symptoms, making the child more uptight and nervous," said psychologist Elaine Leader, director of Cedars-Sinai Medical Center's Teen Line ((800) TLC-TEEN), who has a private therapy practice in the Beverlywood area of Los Angeles. "Or if you manage to get rid of that habit, you might get (a different habit)."
* Encourage other avenues of expression. Children can be guided into expressing their feelings both verbally and physically.
"That's the healthier way, for kids (to) learn to be able to talk about their feelings . . . so they don't have to express them in these indirect ways," Elkind said.
Exercise, experts say, uses up nervous energy and is a way for children to release tensions.
"You find if you take kids out and give them enough physical exercise, they aren't going to be twirling their hair. They won't have time to pick their nose or thumb suck," said Beverly Neuer Feldman, a Los Angles-based psychologist and author of "Kids Who Succeed" (Macmillan, 1989).
* Make the child more aware. Because youngsters engage in their habits without thinking, one answer is to make them more conscious of what they are doing.
Sometimes a child's friends will accomplish this through teasing. A thumb-sucker or nose-picker will bear the brunt of jokes by elementary schoolers. Often taunting, or just a parent's simple request, causes a child to restrict his habit to his bedroom before giving it up, experts say.
Another idea is to have the child stand in front of a mirror and, for example, repeatedly twirl her hair for 10 minutes. After a time, the schedule is repeated, Leader said. Not only does she get tired of twirling her hair and understand how it looks, but the habit becomes something she can control and manage to break.
* Wait it out. Although some youngsters persist in twirling their hair or biting their nails into adulthood, they are in the minority. Some experts conclude that if gentle measures prove ineffective, parents should ignore the habit. Most habits, they say, will eventually go away, albeit as late as junior high school, when social pressures escalate.
Feldman said she bit her fingernails until her teens, when she became interested in boys. "It usually takes care of itself. You rarely see an 18-year-old chewing on his toenails or sucking his thumb," she added. "I think they outgrow it."