Anxiety (which is often brought on by a stressful event) is probably the most common cause of difficulty falling asleep. This is called “stress-related insomnia.” It is a self-limited problem that usually resolves over several weeks (sometimes several months). It does not tend to turn into chronic insomnia.
It might be helpful to reassure your child that it is normal to have difficulty falling asleep after a stressful life event, and that they can expect their situation to improve over the next several weeks.
Times like this are trying for parents. We don’t want our children to experience pain, much less to help them embrace pain. But what an honor it is to be able to help our children face the truly difficult issues of life, and grow into mature, well-adjusted adults.