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Nocturnal polyuria: FAQ

Patient information A-Z

Why does it happen?

Nocturnal polyuria means passing large volumes of urine at night, but normal amounts during the day. There are a number of possible reasons why you may need to get up at night to pass urine; these may include:

  • poor sleep patterns
  • your bladder or prostate are causing you trouble
  • you are producing too much urine at night (nocturnal polyuria)
  • any combination of the above

What will the doctor ask me to do?

In order for your doctor to work out the main cause for your symptoms, he/she will ask you to complete a frequency/volume chart (voiding diary) on which you record the time and amount of urine you pass every time you go to the toilet, as well as the amount of fluid you consume.

Why do I produce too much urine at night?

The body normally produces a chemical from the brain at night which tells the kidneys to cut down the amount of urine produced whilst you are asleep. This chemical is called antidiuretic hormone (or ADH). When you are young, ADH reduces urine production so that you produce less than a fifth of the 24-hour total at night.

As you get older, especially after the age of 65, you should still be producing less than a third of your total urine output at night. When you produce too much urine overnight (ie more than one third of the daily total), this is called nocturnal polyuria. There are a number of causes:

  • you may not be producing enough ADH (vasopressin)
  • you drink too much in the evening; this may include eating foods with a high water content (eg fruit, vegetables, salads, pasta & rice)
  • you use the night-time to get rid of any excess water from your body

Many people develop swelling or puffiness of the ankles in the evening but notice that they are normal, or less puffy, in the morning. This is because, when you lie down, the water which causes the puffiness passes into the bloodstream and is converted into urine by the kidneys. Once this urine is passed to the bladder, it wakes you up during the night with a full bladder.

How can I help myself?

Your doctor will, of course, ask you about your eating and drinking habits in the evening and will examine you to see if there is any ankle swelling. However, there are some things you can do yourself:

  • adjust your drinking and eating to take in less fluid in the evening
  • eat most of your water-containing food earlier in the day
  • if your ankles are swollen, put your feet up as often as possible to help your body get rid of the water during the day; this is not, however, an invitation to become a ‘couch potato’
  • increase your exercise levels (especially walking) because this helps to push excess fluid back into the circulation where it belongs

Other information

This leaflet contains guidelines and advice from professional bodies, together with information about the prescription of drugs. Treatment of patients will be planned with the consultant responsible for care, taking into account those drugs which are or are not available at the local hospital, and what is appropriate for optimum patient care.

Who can I contact for more help or information?

Oncology nurses

Uro-oncology nurse specialist

01223 586748

Bladder cancer nurse practitioner (haematuria, chemotherapy and BCG)

01223 274608

Prostate cancer nurse practitioner

01223 274608 or 01223 216897

Surgical care practitioner

01223 348590 or 01223 256157

Non-oncology nurses

Urology nurse practitioner (incontinence, urodynamics, catheter patients)

01223 274608

Urology nurse practitioner (stoma care)

01223 349800

Urology nurse practitioner (stone disease)

07860 781828

Patient advice and liaison service (PALS)

Telephone: 01223 216756

PatientLine: *801 (from patient bedside telephones only)

E mail:

Mail: PALS, Box No 53

Addenbrooke's Hospital

Hills Road, Cambridge, CB2 2QQ

Chaplaincy and multi faith community

Telephone: 01223 217769

E mail:

Mail: The Chaplaincy, Box No 105

Addenbrooke's Hospital

Hills Road, Cambridge, CB2 2QQ

MINICOM System ("type" system for the hard of hearing)

Telephone: 01223 217589

Access office (travel, parking and security information)

Telephone: 01223 596060

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Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

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Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151