So after searching for about 1.5 hours now in these forums and others for a working addon that makes a sound while your sleeping if a gm whispers you, i finally found one . all the others were not working, and i searched these forums very closely, and found nothing like this, so very sorry if I goofed and there is on, its very early in the morning / late at night.
Okay so the addon is: ... Im not allowed to post URL's so go to curse gaming (search google) and search on the site ChatEventMonitor (all one word) and thats the addon you need. it works for 2.0
What you do is once you get in game type /cem
go to the edit triggers button
go to message type select, and pick "Incoming Whisper"
now in the text theres number of things you can put...
It searches the whole text line (not just the message) for the text you put in. I put in "whisper", because I don't get that many whispers on my char so if i do its probably a GM. Now you can probably put in GM, i havent tested this though so I am not sure if it would detect the <GM> thing before a gms name when they whisper you. Remember to check off insensitive if you don't have the upper/lower case exactly matching what you want it to trigger off of. I found the best sound to use (loudest) is probably the boat docking. Test when your done the trigger, (if you use keyword as "whisper" you can whisper yourself anything and it should ding) and then header to sleep! Enjoy!