I saw my physiatrist again today and we talked a bit more about this supplement. She said she most often recommends it for peripheral neuropathy and other nerve problems. For that purpose, she recommends 500 mg up to three times per day.

I had been taking mine in the morning but switched to taking it at night based on some comments on this thread. I think it is helping me sleep better and have more energy early in the day. I do get very fatigued in the late afternoon and evening, though. Since my doctor suggested the multiple 500 mg doses, I'm considering adding back my morning dose or perhaps a lunchtime one?