Children often have little activities which give them comfort and help them settle down. One of the most common habits of childhood is thumb sucking. My sister is 24 years old now, however when she is tired she still sometimes sucks her thumb when she thinks no one is looking.

Babies suck on a bottle or a dummy to pacify them when they are upset so thumb sucking can relax and make children more comfortable. Young children may also suck to soothe themselves. Since thumb sucking is relaxing, it may help send a child to sleep.