Note: BATTERY NOT INCLUDED SMART LIGHT SENSOR: This digital clock has a switch to turn on the back light, so we can read time in dark or in the middle of the night to know the time. And it is absolutely not too bright to bother when sleeping BACK-LIGHT FUNCTION: Touch the snooze button at the top of this digital alarm clock, the display will light up for 5 seconds. It helps to check the time in dark if its too dim to see BATTERY POWERED: Since it is battery powered you can put it wherever you need it. This product adopts LCD display screen with low current. It is recommended to use 3*AAA carbon battery instead of alkaline battery NOTE: Because this alarm clock adopts LCD screen display and low power consumption, it can work for a long time when you use a brand-new battery. When the battery runs out, the LCD screen will dimout. Please replace the battery to make it work normally again