Utilize the Timer Button to power on/power off after a certain number of hours to fit your usage habit. Set the timer to go off after you fall asleep so that the unit will stop generating cool air once the room temperature has reached a suitable temperature for sleeping. This way energy efficiency of the unit can be optimized. Besides, if you are using a Portable Air Conditioner, make sure you install the exhaust pipe and window seal properly to prevent the exhaust air from affecting the temperature in the room.