This b22 3w light bulb has a cool secret it has a light sensor and so automatically turns on when it senses darkness and off again when it gets light ideal for lighting hallways landings or indeed any space that could benefit from being lit throughout the night this handy little bulb turns your usual lamps into night lightsr r led dusk til dawn sensor bulbautomatically turns on when ambient light drops below 10 lux duskwhen ambient light reaches 15 lux dawn the bulb will automatically