Why do I always wake up at night to urinate four times at the most ' I am female 5o y r s old?

Fluid redistribution. I find many of my patients complain of this. It is caused by several things. Fluid that collects in your legs during the day redistributes to your body at night when you legs are elevated and must be excreted. I usually ask my patients to avoid drinking fluids at least two hours before sleeping and to take diuretics earlier in the day.
Lots of things. See a doctor to check for bladder infection, heart disease and diabetes. Then make sure you cut off liquids 2 hours before bedtime. A urologist can determine if you empty your bladder fully.