"though never clinically depressed, i discovered the powerful side effect of tramadol while taking 150 mg/day for chronic sciatica.  the unrelenting pain was a real downer, but the tramadol reliably helped me maintain an optimistic, upbeat attitude.  during five years of taking it, i never had to increase the dosage for the desired effect.  the downside is that it often interfered with sleep so that i found a mid-day nap essential."