Daytime Christians

It would be somewhat of an outrage to see someone wandering around in the daytime, drunk and disorderly.  Although not recommended, to see the same thing at night is not such a surprise.  In 1 Thessalonians 5:4-11, Paul employs this metaphor to the Christian life.  People who are of the "day" should not be seen as sleepy and inebriated. Christians are people of the day. 

To live in the light -- to live in the day, is to suggest alertness -- morally and spiritually.  Such drowsiness is inconsistent with children of the Light.  So again, Paul lays out the indicative:

⁸ But since we belong to the day, 

and then moves into the imperative:

let us be sober, having put on the breastplate of faith and love, and for a helmet the hope of salvation.

Our identity in Christ is children of the day; children of Light.  Our activity in Christ is to be spiritually sober and alert - bearing the graces of Christ.