Apparatuses and methods to sense proximity and to detect light. In one embodiment, an apparatus includes an emitter of electromagnetic radiation and a detector of electromagnetic radiation; the detector is configured to detect electromagnetic radiation from the emitter when the apparatus is configured to sense proximity, and the emitter is disabled at least temporarily to allow the detector to detect electromagnetic radiation from a source other than the emitter, such as ambient light. In one implementation of this embodiment, the ambient light is measured by measuring infrared wavelengths. Other apparatuses and methods and data processing systems and machine readable media are also described.