Welcome to PC NickelBuster

Admittedly, I'm on a lower dose than yourself (150mg), but also relatively long term (3 years). Though I am aware that this medication can make you very drowsy (especially at a higher dose... a friend of mine said that it left him feeling like a zombie), it's primary use for me as prescribed was as a mood stabilizer rather than for my depression and anxiety. I could be very wrong, its just I've not heard for this to me used primarily for sleep... other meds as a prm such as zopliclone do that for me.

Would it be worth speaking to your dr about sleep specific medication, at the very least as a go to if sleep escapes you? I say this latter part, as I use sleeping tablets very sparingly (due to their addictiveness).