Jamieson, Fausset & Brown

This verse is to be taken in the literal sense. Night is the time when sleepers sleep, and drinking men are drunk. To sleep by day would imply great indolence; to be drunken by day, great shamelessness. Now, in a spiritual sense, "we Christians profess to be day people, not night people; therefore our work ought to be day work, not night work; our conduct such as will bear the eye of day, and such has no need of the veil of night" [EDMUNDS], (Th1 5:8).