While wearing and attuned to these luxuriant slippers, you may choose to become somnambulant whenever you are rendered stunned or unconscious. You remain somnambulant until the triggering condition ends.
For the duration, a somnambulant character is blinded and deafened, but can continue to move at half speed and may take either one action or one bonus action during their turn. A somnambulant character cannot concentrate on spells, and must pass a DC 15 Constitution saving throw before casting any spell that does not include an attack roll. If a somnambulant character has 0 hit-points, they must make death saving throws as normal. A character may rest, or continue to rest, while somnambulant.
After you use this ability you may not do so again until dawn the next day, unless you choose to gain one level of exhaustion, which is gained once you are no longer somnambulant.
Notes: Blinded, Deafened, creature capable of sleeping, Buff, Footwear
While this item may take a little bit to digest at first, basically it's a pair of slippers that if you wear them and get knocked out, you can still move around and do stuff. I just really love the idea of an old wizard being knocked unconscious and just wandering off in his slippers to go find help.
While it does potentially allow a character to remain up and active when downed, they're not immune to failing death saves so the risk of exploitation is fairly minimal, and hopefully in line with this being a rare item.