Charles Ellicott Commentary 1 Thessalonians 5:7

"For they that sleep sleep in the night: and they that are drunken are drunken in the night." — 1 Thessalonians 5:7 (ASV)

Those who sleep...—As the connection of sleep with night has already been sufficiently worked out, and is not touched upon again in 1 Thessalonians 5:8, the first clause seems only to be inserted for the sake of bringing out the second, and to justify the sudden introduction of the words, “and be sober.” It may thus be paraphrased: “I say, ‘and be sober too,’ for as those who sleep do so in the night, so those who are drunk are drunk in the night.”

It is implied that the streets even of heathen Thessalonica were seldom affronted with the common English spectacle of drunken men by daylight; while among the Jews it was proof positive of sobriety to say, “It is but the third hour of the day” (Acts 2:15). In St. Cyprian’s time, Christians were known from other men because their breath smelled of wine in the early morning through attending the Blessed Sacrament (Epistle lxiii. 15): no heathens would have touched wine by that time.