Clock doesn't light up in the day time or room is bright enough.When room's dark， sensor light enables clock to automatically giveoff soft lights， which is perfect at night.<br>Sensor light can also be close， and please simply pressSNOOZE/LIGHT when you're in need.<br>QuietCare to ensure a good sleep and best working environment.<br>Offers alarm Indicator， snooze， a simple interface， night lightthat lets you rest easily.<br><br>Note:<br>You must use ordinary carbon AAA batteries with this clock (thebatteries are not included).