By now you've certainly seen your baby scared, whether in response to an unexpected noise, an angry tone of voice -- or a heavy-set man with a white beard. These experiences can carry over into your baby's sleep and give her nightmares.
Want to say goodbye to the bogeyman? Think about what your horrified honeybunch is exposed to during the day. Listening to arguments between you and your husband, being left alone and ignored, adjusting to a new childcare situation, and discomfort from noisy animals or machines (like a leaf blower) can be stressful for her. Watching violent programs on TV with you could also contribute to nightmares (your baby can recognize adult-style fear, but doesn't know that what she's seeing and hearing isn't real).
If she has had a passing fright, chances are the bad dreams will subside with time. But if exposure to the source of her terror continues, your infant is likely to keep having nightmares and may exhibit other symptoms of anxiety as well. When you can't remove the offending object or event (it's hard to tell your neighbor to quit mowing his lawn), help her adjust by showing her that these things won't hurt her. Soon enough, she'll realize that there aren't any monsters under the crib.