I had that trouble too and even got so far as falling asleep in bus shelters while waiting for the bus and also once while waiting to cross the road on a sunny day. Sun was so bright I shut my eyes for a second and nearly fell face first into the traffic. That was the point I decided to ask the doctor about it and got sent for a sleep study et all. Turns out I have Sleep Apnoea (or however you spell it) and I stop breathing 14 times per hour during the night. I didn't think it would be that as I don't snore but all the machines say that apparently I do.
Is horrible having to sleep with a mask on though.. and then an eye mask when I have a migrane.. I feel like see no evil, speak no evil... all I need now are some ear plugs and I can be all three monkeys in one!!!
Hope you get yourself sorted out soon girly!
Numpty:- (num-p-tee) dialect, chiefly Scot, ~n. 1. a bumbling fool: one who is intellectually challenged. 2. widely known in Scotland as an MSP (Member of Scottish Parliament).