I've taken it for about 5 years for sleep ME/CFS. I find it takes a good 12 hours to wear off but without it I really don't sleep - perhaps I am addicted to it to a degree now but I needed it when i started it and it seems to still work.
Did you post on another thread about feeling because you're not in pain it can't be CFS/ME? Pain isn't one of my main symptoms, apart from headaches and migraines, and some aching joints if they get particularly cold or over used. yet i was diagnosed as a classic case by my local CFS/ME service. I've been badly affected for 6 years. Technically "moderate ME", but I can't read books for migraines, use a mobility scooter to get around outside the house (I'm 35 and used to be very active), have difficulty showering, cooking, thinking, talking at times, a million things. Light head and dizziness has also been a long term symptom of mine, certainly help by lying down. I went through a period of having to lie down pretty much all the time - got up once an hour to get a drink or visit the loo etc, pin the advice of my doctor, but sitting for more than a few minutes made me very light headed. That thas imprtoved, though i can't stand for long (usually use a shower seat eg).
I should add I'm quietly content with my life at the moment, with lots of sleep and careful pacing, DP does a lot for me, and I do craft things to keep myself sane.
Pacing is key - learning your limits, learning how to use you energy in the best way, learning how to gently push what you can do to male gentle improvements.
Good luck.