Frequent urination is a condition defined when the need to urinate is felt several times an hour, caused by the false impression of once again having a full bladder. The quantity of urine passed during the day is not, however, larger, as the urinations are very small in volume. Frequent urination at nighttime is called nocturia, and is quantified by how many times the individual has to get up to urinate. This false impression is most of the time due to an irritation in one of the urinary organs. There can be many different underlying causes of this irritation, such as inflammation of the bladder, called cystitis or more commonly urinary infection; or prostatitis, which is an inflammation or benign swelling of the prostate in men.