Yes - OA - temazepam (restoril) is a benzodiazepine with a half life of 8 - 22 hours. 20 mg of temazepam is the equivalent of 10 mg of diazepam (valium).............. so you have not been taking so very much. So your 15 mg is equivalent to about 7.5 mg valium.
If I were you I would taper off slowly - reducing by about 10% per week.
Why dont you go back to your doctor - explain your difficulties and ask for his proposals for taper?
See the post I have just put up about alprazolam.
Unfortunately - when benzos are discontinued you will experience a "rebound" effect - and so if insomnia was a problem before use then you will experience rebound insomnia for a time until the body readjusts to not having the drug.
Take heart - get off now before it becomes more difficult. Your sleep will eventually come back online - you just have to play for time!

Yinksy