this verse is a good one....
I will both lay me down in peace, and sleep: for thou, LORD, only makest me dwell in safety.
In peace I will lie down and sleep, for you alone, O LORD, will keep me safe.
I fall asleep in peace the moment I lie down because you alone, O LORD, enable me to live securely.
In peace in the selfsame I will sleep, and I will rest: for thou, O Lord, singularly hast settled me in hope.
A few commentary notes:
The Geniva Study Bible says:
I will both lay me down in peace, and sleep: for thou, LORD*, only makest me dwell in safety.
* This word in Hebrew may be referred to God, as it is here translated, or to David (or me!), signifying that he (I) should dwell as joyfully alone, as if he (I) had many about him (me), because the Lord is with him (me).
And Gill's Exposition of the Entire Bible:
I will both lay me down in peace, and sleep,.... Signifying, that he had such a calmness and serenity of mind, amidst all his troubles, that he could not only lay himself down in great peace, and much composure of mind, but sleep also, and that as soon as laid down almost; some lay themselves down, but cannot sleep, through the anxiety of their minds; but the psalmist could do both: or the word rendered "both" may he translated "together"; and the sense be either that he would lie down and sleep together with his friends, committing himself and them to the care and protection of God; or that he should lie down and sleep together with his enemies; meaning that he was assured that there would quickly be a reconciliation and peace between them; see Proverbs 16:7.
...for thou, Lord, only makest me dwell in safety; suggesting that his protection and safety were owing to the power and presence of God only; and that was the reason of the tranquillity of his mind, and why he slept so quietly in the night watches, though in such danger from his enemies; or "thou, Lord, makest me only" or "alone", being solitary and destitute of friends, to dwell in safety; finder the shadow of thy wings, encompassed by thy favour, and surrounded by thy power; see Deuteronomy 33:28