Years ago, in your pre-school toddler days, maybe? Or, like millions of grown-ups, do you still suck your thumb today? We do know that the habit usually starts before we are even born, and later it mimics the endorphin boost babies get while breastfeeding. One man of pensionable age spoke about it in the USA, happily admitting he has continued doing it well into his 60s. He could be watching telly, reading, driving, or going to sleep all the while sucking that thumb. Some of the folk there have claimed that constant thumb-sucking can damage and twist your teeth, while others reckon most grown-ups kick the habit in their late 30s, though no-one seems sure why.
Adult Thumb Sucking: How to Break the Habit
Adult Thumb Sucking: Break the Habit | Colgate® Oral Care
Thumb sucking is a behavior found in humans, chimpanzees , captive ring-tailed lemurs ,  and other primates. It can also be accomplished with any organ within reach such as other fingers and toes and is considered to be soothing and therapeutic for the person. As a child develops the habit, it will usually develop a "favorite" finger to suck on. At birth, a baby will reflexively suck any object placed in its mouth; this is the sucking reflex responsible for breastfeeding. From the very first time they engage in nutritive feeding, infants learn that the habit can not only provide valuable nourishment, but also a great deal of pleasure, comfort, and warmth. Whether from a mother, bottle, or pacifier, this behavior, over time, begins to become associated with a very strong, self-soothing, and pleasurable oral sensation. As the child grows older, and is eventually weaned off the nutritional sucking, they can either develop alternative means for receiving those same feelings of physical and emotional fulfillment, or they can continue experiencing those pleasantly soothing experiences by beginning to suck their thumbs or fingers.
Special Offers. Do you remember when you stopped sucking your thumb? Nearly nine out of 10 babies start to suck on their thumb or another part of their hands just hours after birth. For some people, the behavior continues through adulthood. While thumb sucking isn't an issue in babies or young children, adult thumb sucking may be embarrassing and in some cases may pose oral health problems.
Thumb sucking is common in babies and is said to actually begin in utero. Meant as a comforting gesture that mimics the endorphin rush brought on by breastfeeding, the habit should gradually subside in the first year of the baby's life. However, in some, the habit persists even into adulthood.