I've had insomnia on and off for as long as I can remember. I get it in stages for a couple weeks at a time then I have no problems for a while. When I keep a regular schedule of waking up and going to bed at the same time, it goes away. When I start messing around with my schedule, like staying up until 5 AM or 6AM for a couple nights in a row on the weekend, it comes back.
Benzodiazepines like Lorazepam (Ativan) and Diazepam (Valium) are good for the short term to get you back on a regular schedule, but they give you a buzz, are addictive and you start to rely on them to fall asleep. Gravol makes me feel like shit the next day. Imovane is probably the best, it puts you to sleep, gives you no buzz, isn't addictive and you don't get much of a hangover. Regardless, you shouldn't take any sleeping pills for more then a couple of weeks to help regulate your sleeping pattern.