zigbee thread sleep state

The IEEE 802.15.4 standard supports sleeping devices, which spend most of the time with the radio peripheral disabled. This functionality is used for efficient device power management in both Thread and Zigbee protocols.

To conserve battery life, the SED remains in sleep state until an active state is needed.

The sleep state reduces energy consumption through any of the following ways: 

Turning off all unnecessary modules and peripherals
Putting the CPU in a low power state or disabling it
Using dedicated low power peripherals when needed
Pulling up unused GPIO pins to avoid current leakage through unconfigured pins

The amount of current consumed by a device in sleep state is three to four orders of magnitude smaller than while active.

Sleep state