Seeing your baby hit his head against the crib mattress or rails as he's dozing off can certainly be unsettling. Fortunately, it's usually normal. Up to 20 percent of children are head-bangers, and boys are much more likely to do it than girls. It typically starts at around 6 months and slows or stops by age 3. The exact reason for head banging is unknown, but experts generally believe that it's a way to self-soothe. "In utero, a fetus is constantly being jostled to and fro, so a baby may be soothed by the rocking motion of head banging," says Rahil Briggs, Psy.D., a pediatric psychologist at Children's Hospital at Montefiore Medical Center, in New York City. It also may be done to distract from teething or earache pain.
Understandably, you may fear that your baby's habit could cause headaches, bruises, or even brain injury. Not likely. His noggin is tough, and if the banging becomes too painful, he'll stop on his own. So there's no need to pad the crib with bumpers or pillows -- after all, placing soft items in the crib increases risk of suffocation and SIDS.