Torporous Smite

The next time you hit a creature with a melee weapon attack during the spell's duration, your weapon flares with a wave of lethargy, and the target takes an additional 4d6 force damage. The target must then make a Constitution saving throw - on a failure, the target falls Unconscious for 1 minute. 

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the time the target is Unconscious after failing its saving throw becomes 1 hour.