I took this imponderable question my local GP and the answer I got back was to go and get some CBT and why don't I try anti depressants.
I did point out that I wasn't depressed. I was feeling - apart for being knackered - quite fine thank you and had no negative thoughts whatsoever.
It didn't wash.
I was allowed to have some blood tests but they came back within the normal bandwidth. I asked for them to be checked again - maybe look at hormone levels etc?
This time there was a slight depletion in my cortisol levels - nothing to worry about but we'd like you to go see a specialist.
And in fact it turns out that there really could be a problem, a minor one I am sure...
Has anyone else had it?