Dr. Youngquist: That's going to vary depending on how much water you had beforehand. So when you start out in the morning, actually, you haven't had anything to drink all night long. If you think about it, even fasted. You haven't had anything to drink. And most of your hydration status is actually come from mobilizing that's in your soft tissues. It's kind of accumulated in your feet and legs during the day through gravity. And that gets reabsorbed back into the vascular space while you're sleeping. But you can quickly become dehydrated in the morning without having enough hydration because of that, and you're actually have just urinated, not taken in any fluids at all.