Implicit in my first post was the point that I have trouble sleeping at night.
I naturally feel like sleeping at around 6-7am onwards, and don't feel like sleeping any time before that.

I've been through several different medications for it - barbiturates, benzodiazepines, antihistamines, tricyclic antidepressants and more.

Interestingly none of them work (excluding one antihistamine with an interesting side-effect that renders me unable to comprehend my surroundings the next day), which means that I require extreme force of will to sleep at the wrong times and get up the next morning instead of sleeping through the day until when my body says I should wake up. Unfortunately most mornings I don't have extreme force of will - so I regularly miss early morning university lectures.

Not fun.