Q. I'm bothered by painful leg cramps, especially at night in bed. What causes them, and what can I do to get rid of them?

A. Leg cramps are usually caused by a momentary overactivity of the nerves that control muscle contractions. In most people they are harmless and not a sign of some serious underlying condition. They are often triggered by stetching the legs with the toes pointing down. Many people stretch like this in bed while asleep and suddenly wake up with a sharp cramp in the calf or foot. It is better to stretch your legs with the toes pointing up toward you to avoid triggering a cramp. This maneuver will also help break a cramp once it begins.

You may be more likely to have leg cramps after a day of extra walking. People who take fluid pills (diuretics) may deplete their body of minerals like potassium that help regulate muscle function, and may also be more prone to leg cramps.

Knowing that calcium plays a role in muscle function, many people take calcium tablets to treat leg cramps, but usually without success. Doctors frequently prescribe a quinine-containing medicine called Quinamm for leg cramps, but this medicine is not always helpful.

I recommend leg-stretching exercises to help prevent leg cramps.

To perform the stretching exercises, stand facing a wall, about 30 inches away. Keeping your knees locked and your feet flat on the ground, lean on the wall with your hands. Back your feet away from the wall until you feel the muscles in your calves stretch. Hold this position for 10 seconds, and repeat several times after five-second intervals.

If you're bothered by frequent leg cramps, try these exercises daily for a week. If they work, you can judge for yourself how frequently you need to do them to prevent leg cramps from recurring.

Q. I've had diabetes for almost 12 years. I've read about the importance of taking care of my feet, but can't remember where. Could you refresh my memory?

A. I can't overemphasize the importance of good foot care for people with diabetes, who are more prone to skin infections and their complications. A sore on the foot could spell the beginning of catastrophe. This is certainly one condition in which an ounce of prevention is worth a pound of cure.

Get into the habit of inspecting your feet daily for sores, redness or cuts. A good foot inspection should also be part of regular visits to your doctor. Report any worrisome signs as soon as they develop, so they can be treated early.

Wash your feet in warm water with a mild soap. Avoid soaking in medicated solutions unless your doctor advises it. Some people with diabetes have decreased temperature sensation in their feet, and if so, they should check the water temperature with their hands before stepping in to make sure it's not too hot.

After washing, gently dry your feet, including between your toes. If your feet are rough or chapped, apply a lanolin cream. Don't go barefoot. Wear shoes that have plenty of toe room. If you develop corns or calluses, you may gently use an emory board or pumice stone to sand them down, but don't try to cut them, use plasters or otherwise treat them unless advised by your doctor. Cut your toenails straight across, and not too far back (especially for the big toes) to avoid developing ingrown toenails.

If you're not already a member of the local American Diabetes Association affiliate (telephone 657-8303), I'd suggest joining.

Q. What is the body's penalty for a sleepless night, and how long does it take to make up the loss? Does rest without sleep help?

A. The body seems to have its own inner clock that regulates day-to-day rhythms. This includes when and how long people sleep.

When something upsets the normal sleep cycle, people have a tendency to make up for it later. People who get less sleep than usual will not feel rested, and they will sleep longer at the next opportunity. Other than feeling tired and unrested, however, no permanent harm results from an occasional sleepless night.

How long it takes to make up the loss depends on both the degree of disruption and individual characteristics. It takes from days to weeks to adjust to dramatic disruptions, such as occur with long airline flights (jet lag) or changes in work shifts. Less jarring disruptions usually take a day or go unnoticed entirely.

Quiet rest without sleep doesn't satisfy the body's need for sleep.

Jay Siwek is a family physician from Georgetown University.

Send questions to Consultation, Health Section, The Washington Post, 1150 15th St. NW, Washington, D.C. 20071. Questions cannot be answered individually.