Hello Key,
I felt extremely fatigued around that time - and again more recently.
For me, I put it down to the sheer extra mental effort involved in being sober. Not just the constant awareness of being vulnerable - and therefore the vigilance we need to exhibit to stay safe - but also the fact we are present as thinking adults for all of our waking hours, not zonked out half-cut in a comfortable cotton candy delusional state, all our troubles deferred.
Was that a sentence? No wonder I'm tired.
Think the fatigue is perfectly normal, and I would just roll with it and sleep when you can. I rationalized it by thinking that no matter how much time was getting wasted by me being wiped out and tired , it was tiny compared to the wastage from drinking, being drunk , then hungover, then depressed.
Congratulations on your 90 from me too. Marvellous !
Fradley