With severe shaking, a baby’s head will snap back and forth with significant force that can jostle the brain within the cranial cavity, injuring or destroying brain tissue and shearing or tearing the blood vessels around the brain. One in four babies who suffer this brain injury die, and half will have serious, lifelong disabilities, which can include severe brain damage, blindness, hearing loss, learning problems, seizure disorders, paralysis and others. One in four might appear to escape without long-term injury, but that child may suffer a subtler disability.

About 1,200 to 1,400 babies in the US are severely shaken each year, although experts suspect many cases go undiagnosed. Statistics show that the majority of these injuries were caused by parents. Research done by Dr Ronald Barr of the University of British Columbia documents just how much crying a normal baby does.

With research indicating that crying is the number one trigger for shaken-baby syndrome, the hope is that if more parents understand that babies might have long, uncontrollable bouts of crying, they will be better prepared to handle it.

Doctors advise that parents should also learn that not every baby can be soothed. If necessary, parents, they say, should take a break. Do something to calm yourself — like calling a friend or the doctor for advice, and do not return to the room until you are ready to deal with the baby’s crying.