The way Emotions function internally can be understood by observing the Element of Water as it moves from liquid to clouds to rain in the atmosphere.
While we’re awake, our emotions are like a body of water on the earth’s surface. They lie below the threshold of consciousness/sky. As we experience a specific incident, the emotions that are generated surround all the related thoughts. But as previously stated, only about half of what we experience emotionally is made conscious.
So, as the day progresses, all that unconscious material is building up, the way clouds build in the atmosphere. Eventually there is so much unconscious material, we 'fall unconscious'.
In other words, the predominance of unconscious energy is the sleep state. Falling asleep is like the clouds beginning to rain, sending our thoughts and Emotions down to the Earth (our Bodies).
As we slip below consciousness, the Emotions assimilate the data our Minds collected into the vast ocean of the collective unconscious. And the Mind is snuffed out like a match tossed into a puddle.