Hi Ross
It sounds like you have a milder form of sleep apnoea, as waking with a dry mouth is one of the symptoms of this :o You say you've had the problem for 4 years, but do you have any other symptoms? Do you feel you are getting enough sleep, and are waking refreshed, or are you constantly tired during the day?
There are ways to get help, some methods are using chin straps (bit like an odd shaped plaster lol) to keep your mouth shut, or special nose clips to keep your nasal airways open so you can breathe through your nose, or even wearing a mask to help you breathe correctly. But, for all of these you really DO need to speak to your doctor first. I am guessing your doc will ask you a variety of questions to assess how much it's affecting you and will then refer you to a specialist and/or sleep clinic.
Don't be worried about going to your doctor, nor should you feel silly - this problem is more common than people realise and if it's affecting your sleep then it's also affecting the quality of your waking hours. It wont go away by itself, so it really is in your best interests to seek medical help as soon as you can.
Here are some links you can read about sleep apnoea - you should read them and see if you have any other symptoms too.
http://www.bbc.co.uk/health/conditio...papnoea1.shtml
http://www.nhsdirect.nhs.uk/articles...ectionId=19169
I can't stress enough how important it is, in the long term, to get a good nights sleep. We can all survive the odd sleepless night, but if it continues over time, it may affect your physical and mental health also.
I hope some of this helps - let us know how you get on :)