That explains my situation then. It was the company FunDay yesterday and I was playing footy for them. Afterwards I got sozzled on around 6-7 pints with an empty tummy.Alcohol stops you having cycles of REM, which is why you wake up after about 4 hours. A cycle of REM lasts around 3-4 hours IIRC.
I hardly slept a wink and woke up at 2am thinking it was 4am - time for work. Didn't sleep a wink!