If a mage slept for at least eight hours every day of their life, from the first to the last realm, they would reach a completely purified soul by the end of their life. It was a trade of time for the quality of the soul. A soul without past lives was an utterly absurd advantage; in Kayden's opinion, it was a relatively fair trade. Would he do it? It might be extremely beneficial for people without the ability to manipulate souls like he could.
It was a trade of a huge amount of time for a huge amount of strength. Kayden's studies led him to learn much about sleep; our body typically induces it through many hormones and signals. The lack of sunlight wasn't a barrier to sleeping, but it caused our daily cycle to stretch beyond the standard 24 hours. This was a negative in Kayden's view, as it made things more erratic and without pattern.
