The Sleep Stone

The stone he put in its place looked exactly like Jon's stone, except that it wasn't. It was the Sleep Stone. It worked just like the normal stone, except that every time the stone was used, the one making the wish would fall asleep for five minutes, no matter where they were. The wish would always be granted *before* the wisher falls asleep and no one would be able to wake the wisher until the five minutes were up.