So long as they provide suitable sleeping quarters and have clear contracts, employers can refuse to pay employees working 24-hour shifts for time they can be sleeping. In Mendiola v. CPS Security Solutions, Inc., a California appellate court clarified that all employers can exclude sleep time from 24-hour work shifts. Prior to Mendiola, many believed that only ambulance providers could refuse to pay for sleep time for 24-hour employees, given that the sleep exclusion in the state's Wage Orders only applied to ambulance drivers (and attendants). But in Mendiola, the Court held that any employer can refuse to pay for sleep time during a 24-hour shift, provided it has a prior agreement with its employees not to consider the time as compensable. Employers must also provide comfortable places for their employees to sleep, and the sleep time cannot be interrupted. It is unclear how much of a designated sleep period must be compensated if it is interrupted, although certainly whatever time employees must actually work during the interruption must be paid, at a minimum. Mendiola also held that "on call" time must be compensated if employees remain under their employers' control while on call. For example, Mendiola involved security guards who were required to live on-site in trailers, where they could rest and relax but not have guests, pets or alcohol. Given these restrictions, the employees remained under their employer's control such that the time they spent on-call in their trailers had to be paid.