You're sitting at your desk in deep thought, fingers poised above the keyboard to record your next flash of brilliance. In mid-thought, the lights go out, forcing you to wave goofily at the energy-saving occupancy sensor on the wall that has mistaken your lack of motion for absence. To avoid this scenario, some office workers override the sensors to keep the lights blazing all the time-not exactly in the spirit of conservation.

A smart sensor, designed by Narendra Bansal and colleagues at the Indian Institute of Technology in Delhi, could minimize this annoyance. The device studies activity patterns of people in a room throughout the day and week. During busy hours the sensor will require longer periods of apparent inactivity before flicking off the lights. Bansal has begun preliminary discussions with companies that might commercialize the sensors.