Jonas rarely dreams as an indication of how he is different from others in the community. When Jonas has the dream about Fiona they do not discuss it in detail because all that matters to them is that it is an early sign of stirrings.
Everyone in the community has to share their dreams every morning. It is part of the community’s enforcement of restricting emotions. Just like the telling of feelings at night, the telling of dreams ensures that people’s emotions are addressed and dealt with almost immediately. Any lingering emotions from the day might enter dreams, and those need to be addressed so that they can be dismissed.
When Jonas begins his training, he is given strict orders not to tell anyone of his dreams. The community probably fears that the memories will influence them.
He dreamed so rarely that the dream-telling did not come easily to him anyway, and he was glad to be excused from it. He wondered briefly, though, how to deal with it at the morning meal. What if he did dream--should he simply tell his family unit, as he did so often, anyway, that he hadn't? (Ch. 9)
The fact that Jonas rarely dreams is a sign that he is different from the others. It is foreshadowing that Jonas, as Receiver of Memory, will need to be able to collect memories that are given to him. By not dreaming, Jonas is able to keep his thoughts and feelings private even before he begins his training.
When Jonas does have a dream, it is dealt with quickly and efficiently by his family. The dream is influenced by Jonas’s seeing Fiona the day before. He is an adolescent about to go through puberty, and is having a dream related to his emergent feelings for girls. Jonas has no idea what the dream about wanting Fiona to get into the bathtub means, but his parents do because they have been trained to identify early signs of sexual maturity developing in their children. All they do is tell him it's a stirring and that he has to start taking the pills to prevent stirrings.
The community has tight population control. Babies are born fifty a year, only to certain birthmothers, and in accordance with the genetic restrictions of the community. For this reason, they do not want any unexpected pregnancies. The stirrings pills are an early and effective form of birth control. They also seem to have the side effect of ensuring that other emotions are reduced as well. Jonas stops taking the pills because he wants to feel the entire human experience. It seems that the pills reduce all emotions, and not just sexuality-related ones.
He had not taken the pills, now, for four weeks. The Stirrings had returned, and he felt a little guilty and embarrassed about the pleasurable dreams that came to him as he slept. But he knew he couldn't go back to the world of no feelings that he had lived in so long. (Ch. 17)
After Jonas stops taking the pills, he experiences “heightened” emotions not just in his dreams, but in his everyday life. He feels that “his failure to take the pills accounted for some of it” and the memories account for the rest. This seems to reinforce the theory that the stirrings pills limit the range of human emotions. It is one of the reasons that community members are so compliant, even as adults. The stirrings pills are essentially keeping them psychologically children.
Although Jonas only begins to dream after he starts his training and stops the pills, he feels that the memories are influencing his dreams and the emotions that he alone feels in his daily life. He realizes that no one else in the community, with the exception of The Giver, has ever had a real emotion. They are prevented from them by their rituals of feelings and dream telling, which diminish their emotions, and by the stirrings pills. Jonas feels that emotions, good and bad, are necessary to making good decisions. He and The Giver decide to return the memories and emotions to the people.