I can't sleep

Prevously I have mentioned my amazement that people can sleep so easierly...but it has got too much and so now I am back...

Its a sunday evening so baring in mind its a school night i thought i would go to bed earily. This was going well until 11pm when i finally decided to switch the light off... 'ah' i thought 'sleepy time'. BUT then it hit me 'i'm not tired anymore I have so much to do maybe i should just skip the sleeping and get on with some stuff'

Why does this happen!!?? Its driving me mad. I spend all day thinking - 'im sleepy, i want to go to bed' but when it comes to bed time i have the following going through me head:
'I should really write that essay now and maybe a couple of journal, oww im really behind in journal writing but buying the house is taking up a lot of time plus i still haven't sorted whose doing the tea & coffee at the wedding. I feel fat maybe i should go for a run...'

I'm not even a smart person so why do i of all people think to much!? If im never gonna be able to switch off at night at least it could be productive and make me clever! Work with me here mind.