I know now what was causing it: Zyprexa (or Lybalvi) did and Seroquel did, too. I was deluding myself thinking that a low dose of Seroquel was innocuous. It was not.

I am now back on Lybalvi with added Naltrexone which might help attenuate the hunger side effect.

Lybalvi/Zyprexa is far better than Seroquel in other departments, so with it, at least I know that nighttime hunger is the price I am paying for something valuable: say, I do not need naps, whereas on Seroquel I regularly needed naps.