There is a similarity between the experience of falling asleep, dreaming, and waking up, and the process of dying, bardo, and rebirth. It is extremely valuable, therefore, to gain experience of maintaining awareness through the process of falling asleep, dreaming, and waking. This is excellent preparation for dying. Practitioners can also become accustomed to dying through simply observing the death of each moment, the death of an event or activity, the death of a thought.
Battlecry of Freedom by Ngakma Nor’dzin, Aro Books worldwide, 2019, ISBN 978-1-898185-46-8 Part II - the slogans, p. 108/109