zigbee end device sleeping?

Does a zigbee end device go to sleep after 30 seconds of no data traffic?

If so, is there a way to stop this? (without having to poll it every n seconds)

I can't find any settings to stop this behavior.

I also noticed that CTS drops after 30 seconds of inactivity and from then on it just pulses for 9ms every 260ms...

Data send from the co-ordinater wakes the end device and CTS goes back on.