Unconscious

To knock any unit unconscious, its stun damage (grey inner bar) has to exceed its health (red outer bar). Thus a shortcut to unconsciousness is to have friends lightly wound the unit to reduce its health (eg with a few pistol rounds) before or after hitting it with your stun weapon. Tricky but it can save your life.

Stun damage weapons

• Stun Rod, highly accurate hand-to-hand combat, although few soldiers will gladly accept the chance to poke a dangerous alien with a stick, and large aliens will take a few pokes.
• Smoke inhalation (does not affect sealed Power Suits or robots), approx 2 points/round
• Small Launcher firing the area-effect [{Stun Bombs]]

Recovery

Stun damage fades slowly, approx 5 points/round. Medi-kit stimulants will counteract stun damage on application. To revive an unconscious unit, stand on the square where their body is lying and use the medikit until it can't find a target. The revived unit will be standing nearby without any equipment.

Unconscious Aliens

• can be identified by type and rank when picked up (move a soldier to the same square, switch to inventory screen).
• could still wake up, but tend not to pick up weapons
• can be made unconscious if already half-stunned, by a small amount of damage that knocks their health below the stun level. Pistols suggested.
• attract other roaming aliens. Can be used as ambush bait eg if boxed into the Skyranger [Xeno]
• If I'm not mistaken, they turn REALLY vulnerable to explosives in this state. IF, for any reason, you wish to actually kill them instead of taking them prisoner.
• Large, 4 square, aliens NEVER wake up from unconsciousness. Ever.

Unconscious Soldiers

• can be revived by Medikit Stimulant (rate TBD)
• do recover on their own
• can be carried or thrown like objects
• can be thrown up or into inaccessible areas, see Grenades
• continue to suffer from fatal wounds

Knocking a unit unconscious actually replaces it in the game with an "unconscious unit type item". Rumored associated bugs include cloning a soldier where one clone awakens as the other dies, and extinguishing a soldier on fire by knocking him out.