An electronic device (10), comprising a plurality of data storage cells (12), collectively operable in a data access mode and separately in a sleep mode. The sleep mode comprises a period of time during which the plurality of data cells are not accessed and during which a data state stored in each cell in the plurality of data cells is to be maintained at a valid state. The electronic device further comprises circuitry (18) for providing at least one temperature-dependent voltage to at least one storage device in each cell in the plurality of data storage cells during the sleep mode.