It's normal for teething babies to have trouble sleeping through the night because of the discomfort of cutting new teeth. If your baby's teething pain is so intense that it's waking him up at night, chances are there are also other symptoms, like chewing on everything and drooling like mad.
For pain relief, disregard the old wives' tales about rubbing whiskey or another alcoholic beverage on his gums to placate him—it could be dangerous. Instead, ask your pediatrician or dentist whether you can give your child an appropriate dose of infant acetaminophen or ibuprofen. During the day, teething rings and other specially designed chewing toys can be extremely comforting. Often, these objects can also be chilled in the refrigerator, which is a bonus, because the coolness can help take the edge off the pain.
Reaching new milestones, like crawling, can also keep otherwise good sleepers up at night—your baby's just so excited to learn these new skills that he wants to practice them all the time. Another trigger could be separation anxiety, which can set in around now. It can be frustrating to have your baby waking up after you thought you had the whole sleeping-through-the-night thing down pat, but try not to worry. Sleep that's disrupted by teething pain or illness will get back on track once your baby's on the mend, and milestone madness and separation anxiety are usually just temporary phases as well.