The prostate gland in the male reproductive system is located below the bladder, opening into the urethra. Upon ejaculation, it secretes an alkaline fluid into the semen, which aids the movement of sperm. Men aged over 50 years are commonly affected and the symptoms include frequent urination, especially during the night, causing sleep disturbance. Poor flow of urine and inability to empty the bladder completely is sometimes associated with the hormonal changes accompanying ageing.