I'm starting to get out of my terribly unhealthy of drinking about 3 sodas a day. That's literally all I would drink, so I'm sure I was dehydrated.
Now that I'm starting to drink 8 glasses of water a day (it's been about a week doing it regularly) I wake up with extreme cotton mouth. My dental routine hasn't changed, my diet hasn't changed. Why would my mouth be dry in the morning now that I'm finally getting enough water?
And I guess because of that my breath has not been nice either.
I can brush for a long time, use Listerine, and I still have to pop Altoids all the time.Ahh why is my body punishing me for giving it what it needs.

As for the breath, that can sometimes be a result of reducing calories.
(well, not sure about the breath part... talking about cotton- mouth). Even when I wasn't losing weight and eating crap, I STILL had water to drink all day.. it's my only beverage, it's really all I ever had to drink (with a rare soda).. grew up drinking water and always have, so it's the norm for me. And I always have cotton-mouth when I wake! I keep a water bottle next to my bed.. I thought everyone woke up like that LOL