Arduino Sleep Modes and How to use them to Save the Power
Power consumption is a critical issue for a device running continuously for a long time without being turned off. So to overcome this problem almost every controller comes with a sleep mode, which help developers to design electronic gadgets for optimal power consumption. Sleep mode puts the device in power saving mode by turning off the unused module.
learn about how to use sleep mode in Arduino: https://circuitdigest.com/microcontroller-projects/arduino-sleep-modes-and-how-to-use-them-to-reduce-power-consumption