Children -- and adults -- who can't quit are often embarrassed by the habit, which can be costly and cause long-term damage.
Sarah Hudson recalls slipping into a bathroom stall in elementary school at anxious moments to do it. She kicked the habit in childhood, but peering into a mirror today, she still feels a bit self-conscious about its lingering effects on her smile.
Nikki Martin says it, coupled with a satin-edged blanket, is a part of her 5-year-old daughter's daily bedtime routine. Martin said she knows it's a habit that has to stop soon.
"We have been letting it slide because it makes her so happy," said the St. Paul mom.
The urge to suck one's thumb or finger is a survival skill that starts at birth. But at about age 5, when permanent teeth start coming in, it's time to put an end to the habit, dentists say.
Nearly one-third to half of all preschoolers suck their thumbs. The number falls to about 6 percent of 7- to 11-year-olds. But those who don't or can't quit find that thumb sucking can become embarrassing, disfiguring and expensive. Fixing the effects of a prolonged sucking habit often requires a full mouth of braces, costing upwards of $5,000, and may not completely reverse the damage.
"When you continue sucking beyond the first year of life, it more generally becomes a habit and affects the position of your teeth, the shape of the roof of your mouth or your palate," said Twin Cities pediatric dentist Dr. Teresa Fong, also an adjunct professor at the University of Minnesota. It can affect speech and tongue position, too.
As children get older, they realize that thumb sucking is something they shouldn't do and they may become secretive about the habit, hiding it from friends. Numbers of adults who suck a thumb or finger are harder to discern. Many don't disclose it to health care providers.
Bloomington speech and language pathologist Jennifer Connelly said that one in five of her thumb-sucking patients is a teen or adult. They often come to her for lisps, tongue thrusting and other oral issues but she soon discovers that thumb sucking is the underlying problem.
"One of the biggest misconceptions out there tends to be that thumb sucking is reflective of immaturity," said Connelly. "It's not. It's very simply another comforting or a self-soothing mechanism. Some people smoke when stressed. Some people drink. Some people eat cookies. ... The biggest problem is the social stigma."
Breaking the habit
So how do you stop?
Most kids just need a little coaxing from Mom or Dad. but if they've already tried everything from bandaging the thumb to handing out rewards, it may be time to turn to the small cadre of experts who coach children, teens and adults how to quit.
Shari Green is certified in orofacial myology (disorders of the muscles of the face, mouth, lips or jaw) and is a thumb-sucking elimination expert in the Chicago area.
She said that thumb suckers of any age often have an altered sleep cycle and use their thumb to trigger deeper levels of sleep. After a while, thumb sucking turns into a subconscious habit -- and a vicious cycle.
"The children feel bad about it. They're trying, but they don't even know when [the thumb] goes in. The more negative [an attempt to stop] turns, the more they suck to comfort themselves."
Connelly said that the key is to eliminate the shame and focus on positive reinforcement. In her practice, Connelly, who has a post-graduate specialization in orofacial myology, relies in part on her own experience: She was a thumb sucker, too.
Notions that thumb sucking is a symptom of a deep-seated psychological problem are antiquated and simply wrong, she said. In fact, many of her adult patients are educated and successful.
"It's another coping mechanism," she said. "As our world becomes more stressful and demanding, we see more teenage and adult thumb sucking. ... They just need some help learning to stop."
Connelly built her cessation system on associating sucking with something negative and not sucking with something positive. She challenges her patients to set achievable goals and choose rewards for themselves.
"There should be no long-term goals, no Disney World," she said. "They have to understand that sucking is an immediate need."
Connelly also recommends finding alternative self-soothing routines. It can be a lavender bath, warm milk, Chamomile tea. For children, she suggests more cuddle time.
"Thumb sucking is a very sensual, soothing kind of behavior. We want to replace that with cuddling, hugs and time with parents," Connelly said.
The time it takes a child or adult to stop depends on how long they've had the habit and their will to stop. Connelly said in her 18 years in practice she's only had two patients who didn't complete the program. But for most, they're ready to put the habit behind them.
"It's nothing but a lot of kudos, positive reinforcement and no shame," she said.
Shannon Prather is a Shoreview-based freelancer writer.