by Will Boggs, MD

Last Updated: 2009-07-10 17:08:05 -0400 (Reuters Health)

Increased sleep duration is associated with a higher risk of nocturia, according to a report in the July BJU International.

"As there seems to be a close relationship between sleep disorder and nocturia, physicians should ask patients with nocturia carefully about length and quality of sleep and causes of waking up during sleep," Dr. Masahiro Nakao from Meiji University of Integrative Medicine, Nantan, Japan, told Reuters Health. "Physicians should also ask about nocturnal voiding in those complaining of disturbed sleep."

Dr. Nakao and colleagues compared the number of nocturnal voiding episodes and other variables obtained from bladder diaries, with special attention to the duration of sleep in 694 patients, 162 of whom were suspected of having definite urinary tract pathology.

Twenty-four-hour urine volume, nocturnal urine volume, and sleep duration increased in parallel with nocturnal voiding episodes, the authors report, whereas maximum voided volumes in the day and night decreased with increasing nocturnal voiding episodes.

In multivariate analyses, age, nocturnal urine volume, number of daytime voids, night-time maximum voided volumes, and sleep duration were independently related to nocturnal voiding episodes.

These factors were independently associated with nocturnal voiding episodes even among the 450 participants with no 24-hour polyuria.

"I think other studies to evaluate depression, sleep apnea syndromes, et cetera, are necessary for patients having nocturia and insomnia and/or daytime general malaise," Dr. Nakao said.

"Nocturia is a multifactorial disorder," Dr. Nakao explained. "Four main causes of nocturia are thought to be 24-h polyuria, nocturnal polyuria, decreased bladder capacity at night, and sleep disorder. It is necessary to take all these factors into consideration to treat patients with nocturia."

BJU Int 2009;104:75-79.