I take it for anxiety, which works very well for me. It doesn't make me tired though. I also take Seroquel for sleep, and I find that the gabapentin is causing more weight gain than the seroquel. I might eat my desk or chair if I run out of food.

Unfortunately I think all non-narcotic drugs for insomnia have weight gain as a side effect. You could maybe try some other antipsychotics like Zyprexa or even thorazine.