if i take the prescibed dose as prescribed it makes me sleepy, I take less in the morning and more at bed time, helps keep pain from waking me during the night. My total daily dose is not as high as yours, and the body may react differently to it; ie overcome come the drowsies and cause sleeplessness.
Talk to your doctor about it, would not want it to cause a bad reaction to another sleep aid. Info on the web about Gabapentin is a bit scary.
I took its for a long time and never noticed any problems when coming off cause it is just a NSAID which is just a anti inflammatory med.
i had a ex that took gabapentin...but he never had trouble sleeping.....have you tried over the counter sleeping aids? melatonin? do you take the gabapentin right before bed? If so, try taking it quite a bit earlier. Sorry i wasnt much help. I dont know enough about the drug. Good luck and God bless
snowflake