I work shiftwork about 6 times a month, meaning im up all night and sleeping in the day. I have to admit its always easier if i make the room pitch black, which i can do with a screen on the window etc.

As regards to going to bed by 9pm, i have difficulty doing that.. and i tend to find sleep works in cycles, so if i do to bed when im not tired, i will lie there for several hours until the next "tired cycle".

I guess over time you could get into the trained habit of going to bed when the sun goes down.. might require a bit of work in this day and age :-)