What Causes Frequent Nighttime Urination?

I feel almost desperate. I need to urinate just about every hour during the night. It is a “normal” amount of urine, but then in the morning I feel terribly — almost flu-like most of the day (not tired). This has been going on for many years. I rarely go a few weeks without this problem. My legs and feet swell during the day. I am not on diuretics, as I experience side effects. I am a 60-year-old retired female. Is there a name for this, and is there anything I can do? I do not drink any liquids after 6 p.m. It seems to have something to do with me lying down, because I don’t have this problem during the day. I get up an average of six to seven times each night.

Although I cannot diagnose your basic problem, I believe I can explain it and perhaps offer some suggestions to improve the situation.

Blood and tissue fluid, or lymph, circulate in our bodies through three interconnected systems: the arteries and veins for blood, and the lymphatic system for tissue fluid. Pressure in these systems causes the fluids to flow. In the case of the arteries, this is commonly measured and is called blood pressure. There are also many different pressures in each of the systems, which vary in all parts of our bodies.

Think about the difference in the pressure between a large artery in your brain and a large artery in your foot when you are standing up. Not only is the blood pressure supplied by the force of your heart’s contraction, there is also the hydrostatic pressure of your height. In other words, the weight of a column of blood 6 feet high (if you’re 6 feet tall). So the pressure in your foot artery is actually much higher than the pressure in your brain artery. And the same hydrostatic pressure affects the blood in veins and in lymph channels. This hydrostatic pressure tends to force fluid out of the arteries and veins in the legs and feet when we are standing and sitting. Fluid forced out of these vessels becomes tissue fluid, which is fluid that is between the cells in the tissue. When this fluid is excessive, it produces obvious swelling and is called edema. Edema is almost always most prominent in the legs and feet at the end of the day. Many conditions — heart, kidney, liver diseases, varicose veins, and others — can increase the amount of tissue fluid formed in the legs and feet during the day.

Tissue fluid is collected by the lymphatics and returned to the blood through a connection with a large vein near the heart. There is no pump like the heart to push the lymph up against the force of gravity, which is creating the hydrostatic pressure. Muscular activity in the legs tends to force the fluid up, as it forces up the blood in the veins. Age, inactivity, swelling of the lymph channels, and varicose veins make the valves ineffective. Thus, this pumping action doesn’t work as well, and the result is edema at the end of the day.

So what happens when you go to bed at night? Your body is horizontal. There is no longer any hydrostatic pressure difference between your head, your heart, and your feet. All of the tissue fluid that has accumulated during the day in your legs and feet returns to your blood through the connection near your heart. Your kidneys think you have too much fluid in your arteries and excrete that fluid as urine. You have to get up six times per night to empty your bladder.

Since you have had this problem for many years, I think we can safely say that you don’t have serious heart, kidney, or liver disease. But do you have bad varicose veins? They could be causing the problem, as could simply eating a lot of salt on a daily basis. Many women also wear stockings that come up to just below the knees, and hold them up by twisting them tightly. This greatly increases edema in the lower legs; if you are doing this, choose another type of stocking right away.

Diuretics help solve the problem by forcing your kidneys to excrete salt and water. There are many different ones; if you have had side effects with one, you might try a different one in consultation with your doctor.

The best solution, however, would be to prop up your feet above your hips whenever you are sitting down, watching TV, even eating. Get elastic hose that will squeeze your legs and feet, and wear it during the day. I realize it is not comfortable, especially in hot weather; however, millions of people with varicose veins wear it, and avoid just the problem that you have. Even if you don’t have any obvious varicose veins, the hose will probably be helpful in reducing your problem.

The information provided on Health Search Online is for educational purposes only and is not a substitute for medical advice, diagnosis or treatment.