Books
In the short story "Bad Dreams," books are symbolic of the transition from childhood and the innocence associated with it to adulthood. The young child at the center of the story finds and opens a book. This book is a portal into the adult world for her—a world which she wasn't familiar with.
The passage of time
A recurring motif in the novel is the frequent passage of time. Over the course of their lives, characters must deal with changes in their lives. Many characters transition from childhood to adulthood; other characters move from one season of their life to another.
Houses
In several stories in Bad Dreams, houses are symbolic of a character's inner life. One story, for instance, is set in a house in the middle of the night. The main character moves through the house and finds a room that she has never seen before. That is representative of a part of her that she didn't yet know and hadn't discovered yet.
Memories
Memories, which many characters draw on when reminiscing about their past life, are symbolic of the way that people tend to look at their past rather than look toward their future.
Memory
Characters remembering their childhood are recurring motifs in the novel. The motifs imbue the stories with a sense of lost innocence, past traumas, and pivotal moments that have shaped their adult psyche (and affected their lives forever).