The damage to the brain from being kept unconscious for that period of time would be prohibitive as well.
Drugs aren’t some magic switch, people. You can’t just “turn off” a brain for twenty years.
Issues of the ability to defend yourself aside, I don’t think it’s punishing enough. If you commit a crime, going to sleep for 20 years doesn’t seem like punishment, but 20 years doing hard time behind bars - that is punishment.
IMHO.
Esprix