@Sister Cripes. Well that explains it.
As I said, I haven't had too bad a run with fatigue. And it definitely was that. Today I'm tired (it's been busy) but I'm able to be upright without the overwhelming urge to lie down.
You're right about it being confidence destroying @Zoffiel. I think about getting a job, the sustained level of concentration required, the stress, and then coming home to deal with the family, on my own more often than not, and if I then have one of these fatigue attacks at any point...
@kezmusc I haven't had a reaction like this before. I felt good all day, until I didn't!
@Afraser @iserbrown I'm working on improving the tiredness situation. I'm going to bed earlier and improving my sleep 'hygiene'. I'll keep trying.