Bedwetting at night: why are we not all equal?

A team of Japanese researchers has highlighted the role of a protein in the urge to urinate during sleep, which varies from one individual to another.

It's just one of nature's many quirks. Some of us can sleep for more than eight hours straight without feeling the urge to urinate, while others wake up spontaneously in the middle of the night with an urgent need, or even to a wet bed. This phenomenon, called nocturnal enuresis, particularly affects children and the elderly. Now, Japanese scientists from Kyoto University have just highlighted the role of a protein, connexin43 , in this difficulty the urinary system adapts to nighttime.

In a healthy individual, the body functions differently during the day and at night, thanks to its internal clock known as the circadian rhythm. During sleep, the kidneys produce less urine, while the bladder expands to increase its storage capacity.

A more sensitive bladder

Connexin43 is one of many proteins involved in regulating circadian rhythms. It also determines how much fluid the bladder can hold. By studying mice genetically modified not to produce connexin43, researchers found that their bladder muscles remained highly sensitive, both day and night, to nerve signals indicating that the bladder was full. Conversely, the bladders of "normal" mice could tolerate a larger capacity at night without feeling the urge to urinate.

For the researchers who published their findings in the journal Nature Communications , bedwetting could therefore be linked to circadian rhythm disturbances. The study authors do not specify the cause of these disturbances, but previous research has shown a genetic component to circadian rhythm disorders in some cases, as well as the impact of external factors such as schedule changes or mood disorders. Osamu Ogawa's team also points out that other avenues should be explored, such as urine production by the kidneys or a dysfunction of the cortex, the part of the brain connected to the bladder.