What does Proverbs 3:24 mean?

This promise comes in the same context as prior verses: a generally true statement of the benefits of obeying God. Obedience to the Lord is not a magical spell that prevents us from all negative things (Proverbs 3:25; John 16:1–4). However, those who follow God's Word and submit to His will don't put themselves under the same risks as those who are rebellious or depraved. Earlier verses pointed out that following the path which godly wisdom lays out will keep us from stumbling (Proverbs 3:23).

In that same sense, this verse tells us not to fear when we lie down to sleep. Even in the ancient day, fears and anxieties were a major disruption to one's sleep. Living wisely causes us to sleep soundly, because we know the Lord watches over us at night as well as during the day. David explains in Psalm 4:8, "In peace I will both lie down and sleep; for you alone, O LORD, make me dwell in safety." Also, when we honor the Lord and have a clear conscience, we aren't going to be kept awake fearing for the consequences of our actions.

Sleep comes more peacefully if we treasure the Lord's promise to be with us always (Matthew 28:20). When Herod arrested and imprisoned the apostle Peter with the likely intent to execute him the following day, Peter slept soundly. The fact that his execution was planned and guards were stationed around him did not interrupt his sleep (Acts 12:1–12). It is possible he recalled Jesus' prediction that he would die as an old man (John 21:18), and reasoned, "I am not old yet, so I have nothing to worry about. Herod cannot take my life tomorrow." Or perhaps he simply trusted that God would be with him regardless of the circumstances so there was no reason to fear. Wisdom teaches us to rely on the Lord's promises and get a good night's sleep.