Examining factors that affect the need to urinate during nighttime

This study examined factors associated with nocturnal polyuria (NP), a common cause of nocturia (waking up in the night to urinate). Researchers identified age, body mass index, and time spent in bed as factors that can increase NP. Longer periods of uninterrupted sleep and the use of medication can reduce NP.

Nocturia refers to the need to wake up in the night to urinate. It is one of the most bothersome urinary symptoms reported. Nocturia is common in older adults, particularly those who are also incontinent. Nocturnal polyuria (NP) is a condition where the usual day to night ratio of urine production is altered. It is defined by at least one-third or more of urine output occurring during nighttime. NP is the most common cause of nocturia. However, the factors associated with NP are still poorly understood at this time.

The aim of this study was to identify factors that impact NP in older patients.

The data from two separate studies involving 284 women with urge urinary incontinence were analyzed. All women were older, with an average age of 72.9 years. Sleep questionnaires, bladder diaries, and medical backgrounds were examined to measure their association with NP.

65% of women had nocturia (at least 1 void per night). 55% of women met the criteria for NP.

No differences in demographic factors, bladder diaries, 24-hour urine output, and daytime bladder volume were observed between women with NP and those without. Nighttime bladder volume was significantly higher in women with NP. However, the amount of urine expelled during the first void of the night was lower for women with NP (average 226 ml) compared to women without NP (average 282 ml).

Women with NP spent significantly more time in bed and had shorter periods of uninterrupted sleep. Women reporting shorter period of uninterrupted sleep were also more likely to report worse sleep quality and had higher NP regardless of time spent in bed.

Older age, a higher body mass index (excess weight according to height), longer time spent in bed, shorter periods of uninterrupted sleep, and not using medications for urinary symptoms were all associated with increased NP.

Researchers concluded that older age, a higher body mass index, and more time spent in bed are all associated with increased NP. Longer periods of uninterrupted sleep and the use of medication can reduce NP.