By now I'd say I'm a fairly good sleeper; as long as I don't force myself to go to bed earlier than I'm used to, then I can fall asleep within a short while of going to bed, assuming I don't have anything on my mind. However, I can't sleep past a certain amount of hours (I think about five or six in my case) before I start getting restless and waking up in the middle of the night and such.
Though I've had some bouts of insomnia before...there have been some nights where I just can not get to sleep no matter what I try. Thankfully I haven't had any of those lately, and am actually more prone to falling asleep before I decide to go to bed, ah ha.