Sending XBee S1 to sleep mode remotely

I have two xbee s1 modules. The base set in API mode (acting as the coordinator) and is connected to a microcontroller. While the other xbee module (remote) is set in AT mode and connected to a sensor.

The remote xbee module takes reading from the sensor and sends them to the base.

Sometimes I don’t require to take readings from the sensor, so I want to send a frame from the base to the remote XBee module that would put that module into sleep mode. Could this be done? and how? And later when I need the sensor I wake the module up again.

Your help will be appreciated. I am working for a capstone project for my graduation.