1 Thessalonians 5:6 (ESV) … “So then let us not sleep, as others do, but let us keep awake and be sober.”
Usually thieves break into homes at night when everyone is sleeping. Jesus’ second coming will happen, and it will happen with surprise like a thief breaking in, but God’s people should be on … guard, not asleep. The way to be ready for Jesus’ return is not in knowing when he will return, for he won’t give that information. Instead, readiness lies in being alert and sober. The children of the light will be awake and ready when the Lord returns. Paul describes those who constantly expect the Lord to return at any moment. They are not dallying in sin or falling into temptation or being waylaid by their own doubts. We also must walk close to God in daily fellowship with him so that at the Second Coming we will be ready.
This contrasts with the rest of the world, the others of the “darkness” and of the “night” who are asleep at the Lord’s return. The word translated “asleep” (katheudo) is used for moral indifference (see Mark 13:36; Ephesians 5:14). These people aren’t waiting for the Lord, aren’t caring that he could return, and are even getting drunk (the opposite of sober), a metaphor for their moral indifference toward the holy God. “Sober” also means “self-controlled” (niv) and further implies being ready rather than muddled in one’s thinking. Because unbelievers are people of the “darkness” and of the “night,” their lives are focused on their own pleasures and obsessions and not on alertness and moral readiness for the coming of Christ.[1]
[1] Barton, B. B., & Osborne, G. R. (1999). 1 & 2 Thessalonians: life application commentary (pp. 78–79). Tyndale House Publishers.