When an ordinarily good sleeper suddenly starts waking in the middle of the night, something's probably up. Here are a few possible scenarios, but you should contact your pediatrician to get to the bottom of it:
• Teething: This could make your baby very cranky and uncomfortable. Take a look in his mouth. If his gums are red and swollen, or they feel hard when you touch them, he's probably cutting teeth. If this is the case, a little Tylenol before putting baby down may help him sleep.
• Ear infection: This makes lying down rather painful. If your baby is feverish or has been tugging at his ears lately, call your pediatrician. This is a very common childhood ailment; it often goes away on its own or can be cleared up with antibiotics.
• Growth spurt or developmental milestone: It's common for a baby's sleep patterns to unravel right beforehand, so your baby could be on the verge of crawling or walking for the first time.
Updated 2009. Copyright© 2005 Parents.com.