I was prescribed gabap for management of phantom limb pain. Pain wakes me up at night, and my doc said gabap would at least help with that until tolerance builds. It seemed to reduce spasms consistent with what is reported, and tolerance did build so the sleepiness faded. For me, I early-on got one ear plugged (doc said no relation) and later a general ringing in my head. Later, I began to get heart arrhythmia while waiting for sleep (I was taking 600 mg a night), and these symptoms will clear if I skip a day. Gabapentin has a half-life of 5-7 hrs. I was also taking oxycodone once a day, and gabap reduces the effect (so, I wouldn't take oxy *after* gabap). In any case, on off-days my phantom spasms return. Doc hoped to reduce oxy Rx, and I am currently trying double-dose gapab one day and oxy the next (effect of oxy seems to improve with its half-life elimination and a 24-hour break- of course a longer break would be better if I could stand it). Gapap does have a sedating effect that I don't much like in company. Taken just before bedtime, however, I can depend that it will kick-in and keep me sound asleep until morning. After effects are a little synthetic compared to the natural feel of an opiate after-effect.
When I was young, the doctors didn't like to prescribe opiates (I only got limited amounts of codeine) and I horribly suffered for years. As early as last year, my MD told me that my oxy dose was really pretty low and I should consider taking more. Now the docs have changed their minds because of the oxy ODs, and my new MD is measuring his success by how much I change one Rx - wish we had our own lives to live.