Interesting thread, because I've been thinking about this lately.
I play first thing in the morning. That's the part of my day when I have time to do it, and yes, it's often within 15 minutes of waking up, depending on whether me or the wife is taking the squid to school that day. I do drink lots of water, but I've had range issues the last few weeks.
I attribute this to the holidays and illness getting me out of a good practice routine for almost a month, more than the hour of the day. I assume this is an issue that will clear itself up with another week or two of regular practicing, because I've lost range overall of late. Anyway, I hope that's all it is.