If a person masters their sleep environment and ceases to have nightmares, does that increase their chances of successful transition to the light, even if no rescue is involved?

This is an insightful question because we can tell you that someone who has healed their karma will not have nightmares because they will be in good alignment, and their being a match to the divine energetically will prevent unpleasantness within the thoughts at all levels of the mind including the dream state. So this can serve as a guide to the degree of one’s enlightenment, whether nightmares are frequent and noticeable, or rare or absent. The fact people may not recall nightmares at all does not mean they are not happening, but it is always a good sign when the experiencing of nightmares declines in frequency and may stop altogether, at least on the part of conscious awareness—that will reflect a higher state of being in and of itself if not yet a state of completion. It is quite true that in the case of human spirits in limbo, because they failed to transition back to the light on their passing, retain the ability to worry and experience intense emotions of all kinds. Indeed, they can be in agony and perceive even states of torture with full physical sensations imparted to them by spirit meddler tormentors. So this is one of the great liabilities of being in limbo as an earthbound spirit, that one might be living a continual nightmare that never stops except with a Spirit Rescue effort that can successfully raise them up and escort them to the light finally. This is the great blessing provided by the Lightworker Healing Protocol, to help such hapless victims by rescuing them from this state of potential great unhappiness.