The "bardo", or the intermediate state between lives, is a name for dream consciousness. It is only a partial consciousness, and lies between two "lives" in the sense that it separates two waking states, in which there is full consciousness. Partial consciousness means diminished control, which results in dreams being driven by the karma of past experiences and habits. Past experiences and habits are invariably emotional and deluded.
During the day we may cultivate a peaceful, happy, and contented mind. On retiring that evening we may well feel free and relaxed. The room may seem bright and spacious. Yet in our dreams, deep loves and fears make their way to the surface of the mind. Our train of thought becomes disrupted and then lost altogether. The next morning we find ourselves in a "different world". We may feel tired and depressed. The room may appear small and dirty. We have quite literally been reborn into a different realm of existence - "thrown" into a new life by the delusions of the ego.
The ego is like a thief that harvests your crop during the night and steals it; it steals the fruit of virtue, and sows the seeds of non-virtue.