Another way is to force men and women into hypnosis.

A usual way.
One instance, by injection of a narcotic using a prick to your skin, but mainly, by serving food and drink mixed with a soporific in a cave underground, a room at home or of a hotel, or a clinic, and making eat and drink them before entering.
If you feel sleepy, you can not sleep underground.
A sleeping body is just a log for habitual murderers.