It is generally not recommended to leave a portable heater on all night in a commercial setting like a restaurant. For safety reasons, it's best to turn off the heater when it's not needed, especially when the building is unoccupied. Portable heaters are typically safe to use overnight if they have safety features like automatic shut-off switches and tip-over protection. It's important to follow safety guidelines and place the heater in a safe location away from flammable objects. For commercial spaces, it's recommended to have a trained staff member monitor the heater while it's in use to ensure safety.