Only had the one bout of fatigue but boy it was awful. Didn't know what was going on at the time but having read up on it, I reckon that's what it was. I took my Beta after an 8 hour evening shift and woke up in hell that lasted 48 hours.
I tried another shift yesterday to see what happened. So far so good; no wonkiness. Another shift tomorrow then re-assess the whole situation.
Ive started taking some diazepam before bed now too. Stops the twitching and the 'mind working overtime' thing.