Design a power-efficient system using the Arduino UNO with the following functionality:
- Arduino will be in sleep mode to conserve power.
- When a push button connected to the Arduino UNO is pressed:
- Wake up from sleep mode.
- Read the ADC value of a potentiometer connected to the Arduino UNO.
- Print the ADC value on the Serial Monitor.
- Return back to sleep mode.
- The system repeats the process each time the button is pressed.