Altered circadian rhythms and sleep in aging and sex as factors in nocturia

Abstract

Background: Nocturia is one of the most common causes of sleep disruption and of reduced quality of life. This nocturnal tendency to void increases with age, and is reported to affect men more than women. The underlying causes of these age- and sex- related differences have been inconsistently explained in literature. There are age-related changes in sleep architecture and in the day-night rhythm of urine output, but how each of these changes influence nocturnal voiding is unclear. Furthermore, sex-related differences sleep architecture are not well linked to nocturia. Diminished urine output is achieved through urine concentration either via water reabsorption or sodium retention. There is a day-night variation in urine output in humans, with nighttime output in healthy young adults representing about 25% of total 24-hour production. A variety of hormones play a role in fluid and sodium balance, including vasopressin, atrial natriuretic peptide, and the renin-angiotensin-aldosterone system. Several of these hormones have been reported to show day-night variations, but whether these represent circadian rhythms or effects of day-night changes in behavior is not clear. Without understanding how diuretic and anti-diuretic hormones vary across day and night, their role in nocturia remains unclear. Furthermore, if changes in the amplitude of the circadian rhythm of such hormones occur with age, it represents a potential novel mechanism contributing to nocturia, and a potential therapeutic target.