[xiphmont]

Hm, no, non-24 is not just a severe version of DSPS. Or rather he seems to be saying DSPS is really just a less severe version of non-24.

I have it. What I've learned from my doc (a researcher in the field):

It's primarily a specific genetic mutation that affects many of they body's cyclic timers, but relevant here is that the circadian feedback loop is no longer able to lock to a 24 hour day/night cycle at all. The timer technically works. You're perfectly sensitive to light/dark, but you're hitting a PLL with inputs faster than its ability to make meaningful adjustments. That's not the case with DSPS.

Sleep apnea diagnosis is relevant here, it also breaks the breathing reflex timer. Imagine finding out at age 40 that you've not, in fact, slept more than a few minutes at a time your entire life, because you wake up just enough to take a breath every 3 minutes or so when a secondary suffocation reflex goes off.