To kill oneself you need to do something detrimental, which is harmful to the body, damaging to the body.
For your example of using pills to sleep forever, use Violence defintion number 2: a detrimental treatment.
The mind/body separation is a false dichotomy.
I am my body. You are your body.
If one's life has consisted of more suffering than pleasure, suicide is NOT detrimental to oneself, but a mercy.
Death is also a mercy when you're absolutely certain your future will consist of more suffering than pleasure, as in the case of Aaron Swartz.
You're still causing harm to the body. Whether or not it's worse than suffering (in the mind), doesn't matter. It's still violence.