At the risk of sounding like a salesman... have you seen this new supplement?
X-Dream
I'm about to order a bottle for myself as I've been having similar problems lately. My mind just won't seem to shut down at night. I find myself thinking about things only to find that 2-3 hours have passed by and it's the middle of the night and I'm still awake. Eventually I fall asleep but I wake up every morning by 7-7:30. I also wake up probably on average 2 times in the night while I'm sleeping, either to go to the bathroom or just from tossing and turning. There are some good logs of this product over at AnabolicMinds where people are saying it's doing exactly what I want... calming you down so your mind is at ease when it's time to go to sleep and your body can actually fall asleep..
I'd tend to agree with your doctor though with not working out if you're getting lightheaded from the Valium. That's some strong stuff and you don't want to pass out while you're working out. It could happen very easily. The sleep is an issue in your life right now... the weights will always be there. Take care of the insomnia first and the weights will be there for you when you get that taken care of.