Food, service and ambience have long been the fundamental means for differentiating one restaurant from another. Now a new variable is gaining importance as the industry’s labor plight forces a hard decision on operators: When should their restaurants be open?

As this week’s edition of RB’s Restaurant Rewind reports, concepts are adding or forgoing dayparts as they more carefully balance sales potential against the difficulties of staffing for those hours. Brunch is drawing entrants throughout the full-service sector, but the worth of dinner service is being increasingly questioned.

Meanwhile, even brands synonymous with round-the-clock service are skipping overnight shifts because of diminishing head counts—not of customers, but of potential hires.

As Rewind host Peter Romeo notes in this week’s report, restaurant newcomers have been opting out of post-afternoon service for decades. The Restaurant Business Editor At Large suggests that the true instigator might have ben a concept that was a rage in the 1980s but is little known today, called Le Peep.