Let's get a proper discussion about a topic that we're all affected by, bad sleeping habits, all-nighters and chronobiology.

I've heard from many sides how bad it is not to sleep properly, Mathew Walker, Sinclair, life coach wannabes and so on.

I've been wondering how bad is it really? And how bad is working nightshifts? My gf is currently working 4-5 nightshifts per week avg and since I want to put babies into her I'm really worried about how this will affect her aging, epigenetics and other aspects.
I get her though, nightshifts are really comfy, no putting up with people and better pay. And yet I wanna know how bad the drawbacks are since it's not that obvious.,