I clear my throat every 5 to 10 seconds all day every day and it gets worse the more I talk.  I feel like if I don't clear my throat I can't breathe.  My ENT dr told me that i have constant sinus drainage down the back of my throat and that the back of my tongue is thicker than it should be so that is why I do it.  She put me on Flonase nasal spray and it helped some but when I stopped using it the problem became severe again.  I do it so much during the day that it makes my throat sore too.  It drives me crazy!  I don't do this in my sleep but it starts immediately when I get up in the mornings.