If you want to use your air conditioner at night, there are a few things you can do to make sure it runs efficiently. First, close any windows and doors in the room you're cooling to prevent warm air from coming in. Then, set the thermostat to a temperature that's comfortable for sleeping. You can use the Auto or Sleep modes. Finally, make sure the air conditioner's filters are clean so that it doesn't have to work harder than necessary to cool the room. By following these tips, you can use your air conditioner at night without worrying about wasting energy or creating too much noise.