This paper presents the Digital Hourglass, an alarm clock that focuses on the amount of sleep, rather than wake-up times. It follows a simple approach, lighting one LED for each hour of sleep, and physically resembles the interaction with a conventional hourglass: Tilting the hourglass moves ‘time’ between its chambers, placing it in an upright position activates it, turning it by 180° snoozes it and placing it horizontally on a surface turns it off.. Keywords Alarm clock, digitalization, hourglass, LED, physical interaction design, sleep, time