In the early aughts (2000s), a flurry of celebrities “came out” as adult thumb-suckers. The late Amy Winehouse, singer Rihanna, and actor James Nesbitt were all seen, photographed, or admitted to sucking their thumbs as adults.
Many people have nervous habits, from pencil chewing to nail biting to hair twirling. But why would an adult still suck their thumb? The practice is so associated with infantile behavior that adults who do it hide the habit.
Some adults suck their thumbs for the same reason babies and toddlers do: it relieves stress and provides comfort. Many who engage in the practice may do it unconsciously, only noticing when a spouse, child, or friend points it out and asks what’s happening.
Thumb sucking can be an unconscious reaction to boredom. Inactivity, sleepiness, or waiting in line can result in an adult suddenly realizing their thumb is in their mouth when they’re out in public. Many learn to watch out for the habit and indulge only in the privacy of their homes.
Thumb sucking can be a sign of PTSD in children. Adults who have experienced trauma may also display thumb-sucking behavior to cope with a traumatic experience.
Being the victim of a car accident or violent crime could spur an adult to use thumb-sucking as a means of comfort and a way to regain a sense of safety. A person suffering from the aftereffects of trauma will likely exhibit other symptoms like flashbacks, difficulty sleeping, panic attacks, or outbursts of anger.
Thumb sucking can appear in an adult as part of a general pattern of age regression. Often the result of stress or trauma, age regression is characterized by an adult reverting to the behavior of a younger person, even childish things like relying on a stuffed animal or speaking in baby talk.
Adults who persist in thumb sucking can suffer some of the same adverse effects as children, including dental deformation, blisters, or infections if their thumb sucking is aggressive or prolonged. Unlike children, adults have agency in deciding whether they’ll seek treatment or therapy to break the habit.
Some choose not to, believing their habit is a mild form of self-comfort or a harmless, unconscious nervous tic, less troublesome than nail biting or constant fidgeting and less harmful than alcohol, drugs, or overeating.
No one has determined a precise reason why some adults still suck their thumbs. According to surveys, about 10 percent of adults still do it, and more women do it than men (or maybe women are more likely to admit it).
Whatever the cause, adults with the habit must decide if the comfort of thumb-sucking outweighs the potential embarrassment and adverse health effects. Therapists, from hypnotists to those who practice cognitive behavioral therapy, can help adults who genuinely want to quit.