[1_player]

Delayed Sleep Phase Syndrome: https://en.wikipedia.org/wiki/Delayed_sleep_phase_disorder

I haven't been diagnosed, but I've struggled with falling asleep at normal hours my whole adult life: I've tried sleep deprivation, advancing my sleep cycle[1], pulling all nighters to feel really tired in the evening and go to bed at an acceptable time, but it works only for a couple days, then I'm feeling sleepy a hour or two later than the day before, until I'm back going to bed at dawn. It's like having a circadian rhythm of 27 hours, instead of the normal 24/25[2]

The only thing I haven't tried is melatonin, but apparently in the UK you need a prescription to buy it.

1: Basically going to bed later every day, until you go around the clock and are going to bed at the desired time. Not applicable if you have a full time job -- https://en.wikipedia.org/wiki/Chronotherapy_(sleep_phase)

2: https://en.wikipedia.org/wiki/Circadian_rhythm#Humans

[realitygrill]

Have you tried shortening your circadian rhythm with light therapy? Mine's about 26.5 hours and it's been quite helpful, though I have to sit in front of this light for a little over 2 hours every morning.

http://www.cet.org/