Material movers generally work 8-hour shifts, though longer shifts also are common. In many industries that work around the clock, material movers work evening or "graveyard" shifts. Some may work at night because the establishment may not want to disturb customers during normal business hours. Refuse and recyclable material collectors often work shifts starting at 5 or 6 a.m. Some material movers work only during certain seasons, such as when the weather permits construction activity.