What causes an increase in nocturnal urination?

Increased nocturnal urination is generally caused by factors such as mental stress. Excessive psychological tension or insomnia at night may lead to more frequent nighttime urination. However, this increase only involves the frequency of urination, not the volume of urine; therefore, relieving stress and improving sleep can help alleviate frequent nighttime urination. In pregnant women, the enlarging uterus exerts pressure on the bladder when lying flat, which can also result in increased nighttime urination. Additionally, urinary tract stones may cause a foreign body sensation in the urethra and lead to symptoms of increased nocturnal urination.