I think the amount of exercise one gets is an important factor, and that the level of exercise and the quality and/or length of sleep are (somewhat) directly proportional. I get much less exercise now than I did a year ago, and find that it seems harder to fall asleep at nights.
A year ago I was in my last year of school, and often didn't get eight hours of sleep a night because of homework (or playing around; it was college, right? :-). But I got some exercise: I walked to classes, to the library, etc. As a result, I think I slept better than I seem to now.
Now, I drive to work, sit in my cube a good part of the day, and don't "play around" as much as I used to. The stresses are similar (programming computers at school isn't that different than programming them at work) and my lifestyle is similar in terms of home life. But I get no exercise to speak of.
Do you have sleeping problems, and if so, how do you cope with them?
I don't know if I have sleeping problems (haven't been to a doctor to ask), but it wouldn't surprise me if I did. Whether or not I do, I think it would be good for me to start riding my bike to commute to work, instead of driving the car.
/me goes into the storage closet, looking for my bike, and bangs around for a while...
Update: I also watch a lot more TV now than I did then...