Passage
for ye are all sons of light, and sons of the day: we are not of the night, nor of darkness;
for ye are all sons of light, and sons of the day: we are not of the night, nor of darkness;
1 Thessalonians 5:3 When they are saying, Peace and safety, then sudden destruction cometh upon them, as travail upon a woman with child; and they shall in no wise escape.
1 Thessalonians 5:4 But ye, brethren, are not in darkness, that that day should overtake you as a thief:
1 Thessalonians 5:5 for ye are all sons of light, and sons of the day: we are not of the night, nor of darkness;
1 Thessalonians 5:6 so then let us not sleep, as do the rest, but let us watch and be sober.
1 Thessalonians 5:7 For they that sleep sleep in the night: and they that are drunken are drunken in the night.
The verse centers on "light", "darkness", "sons", and "night". It is saying that the contrast between light and darkness marks a real divide in how people respond to God's work.
The nearby context moves from verse 4's "But ye brethren are not in darkness..." into verse 6's "so then let us not sleep as...", so "light" and "darkness" belong inside that flow. In 1 Thessalonians context, the local focus is Christ, faith, and discipleship.
A plain takeaway is to answer the verse's own emphasis on "light" and "darkness" with trust shaped by these words, not by a vague optimism outside the passage.