Is there a Bible verse about sleep and peace?

There are two verses, (both in the King James version), but you may only have been thinking of the one in Psalms:-

Psa 4:8 I will both lay me down in peace, and sleep: for thou, LORD, only makest me dwell in safety.

Eze 34:25 And I will make with them a covenant of peace, and will cause the evil beasts to cease out of the land: and they shall dwell safely in the wilderness, and sleep in the woods.