Just when you think that sleep issues are behind you, and your child is happily sleeping through the night as well as being down to one solid, predictable nap, a new issue arises: night time fears. Around the age of two, continuing up into the preschool years and beyond, children often develop a fear of the dark or of being alone at night. This phase can last a few weeks, but can also extend to a few months or even years depending on how it is handled.