Touch of Sleep

This spell sends a creature you touch into a magical slumber.

A creature of CR 1/2 or less that you touch must succeed a Wisdom saving throw or it falls unconscious until the spell ends, the sleeper takes damage, or someone uses an action to shake or slap the sleeper awake. 

Undead and creatures immune to being charmed aren't affected by this spell.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher you may affect a creature who's CR is equal to the spell slot level minus one.