A medical device, such as a peritoneal dialysis machine, includes a sensor for sensing motion and/or user proximity in the vicinity of the medical device for the purpose of automated dimming a display of the medical device. In the event of a lack of user-activity on a machine interface and a lack of movement detected by the proximity sensor, the machine display is automatically dimmed to minimize power-consumption and provide an enhanced medical device for night therapies in a home or clinic environment. The machine display may be dimmed in the event of an alarm-free machine condition, where no machine activity is detected and/or where no movement is detected by the sensor over one or more time periods. When machine activity is detected, when movement is detected by the proximity sensor, and/or in the event of a machine alarm or warning, the machine display may be automatically undimmed.