Maybe you were lucky when your child was an infant. Unlike your friends' babies, she slept so soundly through the night, with nary a whine or a whimper, that you were convinced you'd given birth to a little angel. Then, just when you started thinking you'd won the lottery, your heavenly baby changed her ways—and started wailing in the middle of the night. What happened?

She grew up, says pediatrician Ronald E. Becker, MD, an expert in child development at the Center for Pediatric Sleep Disorders at Children's Hospital Boston. All babies cry because they are hungry or uncomfortable, but prolonged crying that recurs throughout the night may indicate an important developmental shift. "These changes typically begin between nine months and a year," says Dr. Becker. During this period, babies often find themselves awake for an extra hour each day, often in the middle of the night. They also begin to realize they're alone in their crib—and that their cries will bring you running. In general, it's a good idea to avoid fussing over little ones at bedtime. "Children who receive too much attention when they're put down will be more likely to wake up at night," Dr. Becker explains. If your toddler has a new baby brother or sister who cries in the middle of the night, she may start doing the same, especially if she finds that Mom and Dad will spend time soothing her back to sleep.Sometimes a child's wakefulness has nothing to do with wanting attention, says Dr. Becker. Some young children, usually between the ages of 18 months and 6 years, experience night terrors, intense episodes in which the child is asleep but appears awake. She looks frightened, even panicked, and may scream or thrash about. This can last five to 30 minutes, and the best thing to do is simply wait it out, says Dr. Becker. She'll eventually go back to sleeping calmly, and the next day she won't remember what happened. If your child has chronic night terrors, however, speak to her doctor.If it's just a matter of waking up at night, try not to pick your child up or rock her (unless she seems to be feeling sick). Instead, try speaking to her in a gentle, calming tone of voice until she falls back to sleep on her own. And if the night waking continues, consult your family's pediatrician. After all, the sooner you identify and address the problem, the sooner you'll have your sleeping angel back!   

Needy Night Owls

While late-night crying is often the result of scheduling changes or developmental issues, there are a few other reasons your child may be wailing the blues. Ask yourself whether your little one could be suffering from one of the following, which you can remedy or which will pass:

Fixable conditions

Uncomfortable surroundings, hunger, diaper distress.

Temporary issues

Colic, teething, minor illness.

If you suspect problems like anxiety, serious illness or sleep apnea, get professional help.