No one's life ceases to be any less or more of [a] life (physical existence) when sleeping
You do not have regular human experiences when sleeping. At most you dream, which is a diminished state of mind that occupies about 20% of your sleep cycle. And not everybody dreams either. And what about comatose patients who apparently do not dream?
So then, in a diminished state where you do not experience normal human cognition, is your right to life unaffected? You would seem to answer yes, while denying the same to fetuses and embryos, whose similar lack of experiencing normal human cognition is also temporary.
it is a necessity for good/balanced mental and physical health
So is fetal and embryonic development, including the stages of development predating the formation of the complete brain and in which said brain gradually proceeds toward said development.
A born human being is an actualized human being. Once actualized, that human being never becomes anything less than, that is, until death, naturally.
I say this distinction is arbitrary.
Every future second of your life is no less a potentiality than every future second of a fetus's life; the only thing actualized is the "present", which is as short as the shortest measurable or conceivable unit of time. As the present is constantly terminating in favor of a new present taking its place, killing somebody causes the termination of the present to happen no sooner than if their life were to continue. All that killing somebody does is to deny the replacement of a terminated present with a new present, which is to deny the transfer of potentiality into actuality, which is also what abortion does.
You seem to be arguing it's particularly important that actualized life will continue if not interfered with. But the same is true for the fetus or embryo in the womb. It will continue to develop in the womb and then be birthed if not interfered with.
If you try to draw another line based on the fact that a fetus or embryo requires external support to survive, then the same is true for many people: they have health conditions which rendition them dependent on modern medicine.