Elderly people urinate less during the day and more at night may be normal physiological phenomena such as urinary tract infection, prostate enlargement, etc.. 1. Normal physiological phenomenon: a lot of water or tea before going to bed and other habits, will cause nocturia, in addition to high blood pressure in the evening before going to bed with diuretics will also cause nocturia. 2. urinary tract infection: urinary tract infection is caused by pathogenic microorganisms of the urinary tract infectious diseases, including bacteria, mycoplasma, chlamydia, viruses, etc., the elderly immunity is low, especially do not pay attention to hygiene, more likely to appear in this case, there will be frequent urination, urinary urgency and other symptoms, in the evening the symptoms will be more obvious. 3. Prostatic hyperplasia: this is a common benign disease in middle-aged and elderly men, the main symptoms are frequent urination, urinary urgency, difficulty in urination, increased nocturia and so on. There are many other reasons why elderly people urinate less during the day and more at night, such as neurogenic bladder, diabetes mellitus, prostate cancer, etc. They should go to the hospital in time to find out the cause of the disease and treat it correctly.