Small details, pressures, and traces of waking life begin to settle. Some may remain and reappear in dreams as images or situations.
Past experiences are linked in new ways. Fragments that seem unrelated while awake may meet within the same dream scene.
Lingering emotions begin to soften. What has not been fully felt or put into words may return in symbolic form.
During sleep, the body and emotions can still respond as if an event were actually happening.
That is why some dreams are remembered more like lived experiences than imagined stories.
The stronger the emotion, the longer the impression may remain after waking.