One of the lines that caught my eye in Emergence was "So tell me what you meant by 'living past your half life'?" In chemistry, a "half life" is the time it takes for a substance to decay to half of its original mass.
Further, half lives are also prominent in physics, specifically, nuclear physics. It has the same definition—amount of time taken for a nuclei to half itself—but is, as its name suggests, focused on how much useful energy is produced via the decomposition.
This also links in with the later lyrics of "space dust for your fuel rods." Fuel rods are used in the control of a nuclear decay reaction within a nuclear power plant. This could be interpreted as either Vessel's lack of autonomy, or Sleep losing dominion.
If it's anything to note, "space dust" can also be radioactive.
So, with this all in mind, living past a half life is, in its basics, working towards rot. Existing as a dead man walking and overtly aware that you are.
To me, this could be in reference to Sleep. It's been emphasised that, while Sleep is one of the oldest Gods, He is a forgotten one; kept alive by rituals and those who are beckoned by song to follow Him. Aka, kept alive and powerful by Vessel.
Sleep has long since lived past His so called "half life," and, in toe, He is, therefore "well versed in the afterlife."
While I don't think it works as well, mainly because I consider the majority of this song to be Vessel having a go at Sleep, instead of vice versa, this could be applied to Vessel as a mouthpiece, too, posing the question of; how long until your humanity disapears? How long does it take until you pass your half life, and begin to speak and see only that which bloodless and broken creatures do?
How long until you aren't even you anymore?
And, when that change happens, which it will, eventually, will you emerge and become "someone new," or stay as you were?
