I swear this was a thing once upon a time, and in all my googling I can find a couple of comments from 6-7 years ago referring to this as well, but I haven't been able to find anywhere where anyone mentions if this was patched out? The last few times I tried putting a colonist who was on the verge of a mental break due to some mood debuff (loss of a family member for instance) into a cryptosleep casket, the mood debuff timer also froze.
Logically, this makes sense, but I could've sworn it was a cheesy strat that worked at one point but wondering if I have a case of mendela effect or something on how it actually worked/works.
I've tried all three types: Ancient, Ship, and the regular one. (Important note below)
Edit: Well, now I just feel silly. I don't know why it wasn't working before but now it is...I wasn't paying close enough attention, but it didn't look like the counter was ticking down the couple of times I checked, though now I'm wondering if it's a difference between the Ancient/Normal Cryptosleep Caskets and the Ship one. I decided to construct a simple structural beam and a ship cryptosleep casket, and it actually started working the way I described. I could've sworn I had tried that type as well, but guess not. Either way, this has become moot, and I can at least confirm it does still work, at least with the ship ones.
I'll leave the post up on the offchance maybe it helps someone find it who might google it specifically.