Your body needs water all day. And nighttime is no exception!

But when the question of water comes up, invariably someone will inquire about the embarrassing problem of getting up to use the bathroom. After all, if you're going through 20 or more glasses of water a day, that water's going to go somewhere.

First off, relax. If you're bothered by waking up during the night to urinate, you might want to slack off some a couple of hours before retiring. In other words, if you go to bed at 11:30, you might want to stop taking in water (except for sips) after 9 p.m. In other words, load up earlier in the day, and begin easing off after eating in the evening, and just stop drinking glassfuls after a certain point.

I will point out that there is nothing life-threatening about getting up during the night to urinate. In many cultures around the world, people routinely awaken and go back to sleep several times during the night. Our problem, bluntly, is electrical. That is, electrical lights. See if your routine isn't something like this. You wake up during the night, needing to urinate. You get up, turn a light on, and go about your business.

The problem is a little substance called melatonin. To make a complicated story a tad more simple, your body manufactures it during sleep. And it makes you feel more rested when you get enough, and considerably less rested when you don't get enough. But the instant there's light, the body's melatonin making slows down or quits. Now that's no problem if we're talking about the light you normally get come morning. But the problem is when you turn on a light at 3:30 in the morning in the process of taking care of nature's call. Your body stops making melatonin, and you feel lousy the next day.

So, a couple of sleepy-time rules that may help you feel better. (Remember, I'm a nurse. I've dealt with -- when I was still practicing hospital-based nursing -- trying to ensure that patients got enough sleep. When I was doing that, I was probably working nights myself, and so I was having to sleep during the day. You learn quite a few tricks that help you sleep). In the first place, don't turn on lights. Now since I don't want you breaking a leg in the dark and complaining to me about it, you might want to invest in a nightlight or two -- preferably one that's dim. But whatever you do, if you wake up -- for any reason -- don't turn on a light. Don't decide you're going to read or watch TV or whatever. Just stay there in the bed. That's the logic behind counting sheep -- to bore yourself so badly that you'll just fall back asleep.

The next rule is don't look at the clock. In the first place, what difference does it make? I'm not going to scold you about how Americans are obsessed with clocks (although as a nation, we are), I just want you to ask yourself why it is so important for you to know that you woke up at 3:14 a.m. to use the bathroom. (Listen in on morning conversations at work: people will actually talk about it). But the bigger problem is that by checking the time your mind starts in operating big-time. You start thinking about what you have to do in the morning, or that bill you have to pay, or whatever. Don't allow yourself to do that. Sleep-time is for sleeping. Use it for that. And don't worry if you occasionally have to wake up to heed nature's demands.

But how does water actually help you sleep better?

In sleep, your body is actually going through many (not all) of the processes that are happening during waking hours. Adequate hydration means that all of those processes are able to work well. Your body is digesting food (preferably not too much: that's why heavy meals before bedtime make for a bad night's rest -- your body is working hard when it should be resting), delivering oxygen to the body, etc. Enough water is especially important to your mouth and oral passages, which can become dry during the night. We keep a full glass of water close by, so we can take a sip if we wake up during the night. That prevents that dry and craggy feeling in your mouth that sometimes happens. You are also less likely to snore if your mouth is adequately moist.