@MacMeaties
1 in 227? That's very rare... Leukemia causes anemia too, and it's pretty rare.
Anemia is not really a big deal overall, as you said, it causes tiredness and that's that. A very severe anemia can causes syncopes, but that's also pretty damn rare and not really a serious issue... I think they use it like that because it's such a "no big deal", but it is still wrong, it'd be better to use something else like exhaustion or fatigue. If not sleeping properly caused anemia, I'd be dead from the sheer lack of blood by now.