Smokey, I take 50mg amitriptyline every day for migraine prevention.
The migraine specialist said it's best to start with a low dose and work up to roughly 50-75 mg for pain, IBS-D and migraine prevention. For depression higher doses are often needed.
Regarding sleep, I found that even 25mg made me completely crash out for 8 hours solid.
Despite being an old school type TCA, I think amitriptyline is a great all rounder medication with virtually no side effects and I regret not taking it sooner.
I read up on Mirtazipine but I don't like the sound of the gastro side effects.