Babies have a natural sucking reflex which develops during the intra uterine life, persists during early infancy and facilitates breast feeding.

Interestingly thumb sucking behaviour is also found in chimpanzees and captive ring tailed lemurs. Thumb sucking is one of the most common habits of children but most of them stop thumb sucking on their own by the age of 2-4 years.

It has an incidence of about 25% in < 2 years and 15% under 5 years.

However if  thumb sucking behaviour persists beyond a certain age as a sort of self comforting ritual, it becomes a matter of concern for the parents.

Child may suck his/her thumb out of boredom when hungry or tired or for feeling of pleasure or when going to sleep for comfort or warmth.

It is thought that thumb sucking stimulates receptors in the brain which cause release of tension.

Most experts believe and agree thumb sucker children less than 5 years of age shouldn’t be pressurised too much to stop as they will give up this habit on their own.

No adults are seen thumb sucking.

Thumb sucking isn’t usually a concern until permanent teeth  set in or it causes other problems of frequent infections, jaw pain ,paronychia (infection) of nail folds, speech delay.

To overcome the habit, parents must use positive reinforcement .Praise the child or give small rewards when child doesn’t suck.

Keep reminding the child gently to stop this habit. Also try to identify the triggers which cause such a behaviour as grandma would say from her experience – give more attention to the child.

Covering the thumb nail  with bitter or unpleasant substances  is usually not recommended.

And it is rightly said that there is always a good thing hidden in bad. It has been studied that people who have gone through thumb sucking are less likely to have allergies to pollen and dust mite as by thumb sucking they start building their immunity at a young age.