A form of sleep or somnambulism brought on by artificial
   means, in which there is an unusual suspension of some powers, and an
   unusual activity of others. It is induced by an action upon the nerves,
   through the medium of the senses, as in persons of very feeble
   organization, by gazing steadly at a very bright object held before the
   eyes, or by pressure upon certain points of the surface of the body.