After having a few too many nights where I have been going to bed later and later, and even then not sleeping well, I decided to download F.lux.
It's an app that changes the colours on your monitor as the day progresses. The colours are normal during the day but once the sun goes down the screen colour slowly gets more orange. The screen reddens to spend a few hours at 3400K (halogen) before going even further to 1900K (candle) at about midnight.
The app is aware of your location and makes the changes based on the local sunset time.
I've only been using F.lux for an hour or so. The screen looks pretty orange (it's 9 p.m. here) and I am feeling weirdly sleepy. Apparently your eyes will notice the orange colour less over time but it's pretty weird at the moment.
Based on my limited use so far, I'd recommend that app. Especially good since it's free. I'll have to see how it goes though.