The horror period is an expression of your psychologically maintained sense of hunger, i.e. habit.
Seems to be worse if your diet is bad, too. My worst was when I was drinking rather too much and eating a lot of sugar.
It does get better, though. A lot better.
But it's not an exaggeration to say there are a lot of westerners alive today who have no idea what hunger actually feels like.
(It doesn't just feel like intense cravings, and often doesn't feel like that at all.)