@tekka said:

if(isTransportOK()){
    sleep(30000);  // transport is OK, node can sleep
  } 
  else {
    wait(5000); // transport is not operational, allow the transport layer to fix this
  }

I've only just found this post, and these lines of code have me excited! fixes my problem, thank you!

@ajachierno said:

Also it always seems to be the same value regardless of light conditions (54612 ). I am thinking my sketch is wrong

Your sketch looks correct to me, but if the lux sensor is always reporting the same value, then it will only send the message once as you have seen. Are you sure the lux sensor is wired correctly?