I take 100 mg of Seroquel XR about three hours before bedtime and I sleep all the way through for the first time in YEARS. It took awhile for it to build up in my system but now it works like a charm.

I've had good results with Melatonin too, which is available without a prescription. You take it about half an hour before you want to sleep.

Insomnia is a major depression symptom though. I wonder if your meds are working? Is you doc a psychiatrist? My psychiatrist takes lack of sleep seriously and stays on it until it is fixed. If you are seeing a GP, maybe a meds evaluation by a specialist could help. Hang in there!