Waking at night to pass urine: causes, red flags and when to get it checked

At night the body should make less urine, partly through the hormone vasopressin. If more urine is produced, if the bladder is overactive or compressed, or if sleep is light and broken, you wake to pass urine. In older age, nighttime urine production tends to rise, so nocturia becomes more common.

• Drinking a lot of fluid, caffeine or alcohol in the evening, and evening diuretic tablets.

• Enlarged prostate in men: weak stream, hesitancy, dribbling and incomplete emptying along with nocturia.

• Overactive bladder: sudden urges and frequency in the day too, in men and women.

• Sleep apnoea: repeated arousals and increased night-time urine production, with snoring and daytime sleepiness.

• Type 2 diabetes or high blood sugar: thirst, increased urine and tiredness.

• Heart failure and ankle swelling, where fluid pooled in the legs returns to the circulation when lying down.

• Urinary tract infection, kidney disease, high calcium and menopausal changes.

• Diabetes insipidus and bladder or prostate cancer, which are less common but important.

Blood in urine, pain on passing urine, a poor stream with retention or dribbling, unplanned weight loss, marked thirst, leg swelling and breathlessness, back pain with urinary symptoms, or new incontinence need prompt assessment.

• Call 999 or go to A&E: inability to pass urine with severe lower abdominal pain, or new loss of bladder and bowel control with back pain and numbness between the legs.

• Same-day GP: night-time urination with fever, loin pain or blood in urine.

• GP within weeks: persistent nocturia waking two or more times each night, or with extreme thirst.

• Routine: occasional extra trip after evening fluids.

The doctor asks how many times, how long, daytime frequency, urgency, stream, fluid intake and timing, caffeine, alcohol, medicines, snoring, swelling, thirst and diabetes. They examine the abdomen and in men perform a prostate examination, and check for ankle swelling and blood pressure.

• Bladder diary (frequency-volume chart): shows night-time urine volume.

• Urine dipstick and blood tests: glucose or HbA1c, kidney function, calcium.

• PSA blood test in men, after counselling about its limits.

• Kidney and bladder ultrasound with post-void residual: to check emptying.

• Sleep study: if sleep apnoea is suspected.

Reduce drinks in the three to four hours before bed, cut caffeine and alcohol, avoid late diuretic doses by speaking with your prescriber, and raise your legs in the late afternoon if they swell. Treat constipation, which can irritate the bladder. Bladder training helps overactive bladder.

The NHS route is a GP with diary and tests, then urology, a continence clinic or sleep service. Private urology and sleep services offer direct access to tests.