Bladder spasm/overactivity (as in overactive bladder, with or without urge urinary incontinence – see.Bladder obstruction (blockage) from spasm of the urethra, urethral stricture (partial blockage of the tube that empties the bladder), or a mass/tumor on the bladder or another pelvic organ.This, over time, reduces the bladder’s ability to hold urine. Sleeping disorders which interrupt sleep, leading to more frequent bladder emptying during the night.Low nighttime bladder capacity may be caused by: Medications such as “water pills,” some heart medicines, demeclocycline, lithium, methoxyflurane, phenytoin, propoxyphene, and high dose Vitamin D.Once you lay down at night, the fluid shifts to the kidneys where urine is produced. Swelling of the legs as a result of fluid accumulation during the day.Congestive heart failure – a condition in which the heart does not pump blood through the body efficiently – can result in a large amount of fluid gathering in the legs and a decrease in blood flow to the kidneys, which is the cause of urine production during the day.High blood sugar can make you thirsty and the resulting high fluid intake leads to polyuria. Untreated or poorly controlled diabetes.High fluid intake, especially in the evening.Nocturia is generally caused by polyuria (an excessive or abnormally large production of urine), low nighttime bladder capacity (not being able to hold enough in the bladder at night), or a combination of these.

Night time polyuria