Symbolism, Imagery, Allegory
Without sleep, we turn into walking zombies in desperate need of Starbucks. Parents all over the world have invented little songs to get their children to just go the heck to sleep already. But for Paul and the early Christians, falling asleep was not a good idea. Were they afraid of the dark? Or was there something else going on?
You Snooze, You Lose
Paul warns the Thessalonians not to nod off to sleep while they're waiting for Jesus to come back. Quick! Someone break out the No-Doz.
Let us not fall asleep as others do, but let us keep awake and be sober; for those who sleep sleep at night, and those who are drunk get drunk at night. But since we belong to the day, let us be sober, and put on the breastplate of faith and love, and for a helmet the hope of salvation. For God has destined us not for wrath but for obtaining salvation through our Lord Jesus Christ, who died for us, so that whether we are awake or asleep we may live with him. Therefore encourage one another and build up each other, as indeed you are doing. (1 Thessalonians 5:6-11)
What does Paul mean by this? He's basically saying that Christians need to stay on their toes. They need to be alert and ready for when Jesus comes back. Mainly, that means living good Christian lives and not slacking off at all.
Night and Day
He ties this in with another one of his favorite images: light and darkness. In Paul's world, light means that people can see the truth about God and follow a good and righteous path. Darkness is synonymous with wickedness. Those who are in the dark can't make out what God wants to tell them. Maybe if someone could hand them a flashlight, they would be able to get a clue.
He tells the Thessalonians, "You are all children of light and children of the day; we are not of the night or of darkness" (1 Thessalonians 5:5)—meaning that they are meant to act in a holy and illuminated way at all times. They should never give into the darkness and fall asleep. No matter how tired they get, they've got to rage against the dying of the light.