When waking up to joy in a dream, it means that you are in compliance with your morals and values on making decisions. In another sense, it might be a reflection of how we feel physically after going through difficult moments or just able to cope with stagnant feelings.
Dreaming about joy can be a reflection of loved ones, delighted celebration, a few good breaks, receiving or delivering something important or life-changing. It is also an emotion created by our many good experiences and is most able to use and stack these experiences to improve ourselves.