Yeah it's pretty bad giving it up.
When I gave up I quit ciggies and painkillers also and it was a nightmare.
Insomnia, really strange vivid nightmares when I did fall asleep. Waking up in pools of sweat.. felt like time was going so fast through the night, like 8 hours of sleep felt like a 30 minute nightmare
I ended up having to get valium to level myself out at night because at times it felt like my heart was going to explode from my chest.
Drank lots of green tea with added Hawthorn Berries to keep blood pressure down. It took me a few months to adjust after giving up.