When we go to sleep at night, our bladder's capacity increases in order to allow us several hours of undisturbed sleep without needing to wake up and empty it.
Now a team of Japanese scientists has discovered the bodily process that causes this to happen, offering a possible explanation of why some people are troubled by the chronic need to visit the bathroom during the night.
A study on mice by researchers from Kyoto University found that the body's production of a protein known as Cx43 is linked to the body clock that tells us when to wake up and go to sleep, and to our ability to control our bladders.
The scientists, who published their study in the Nature Communictions journal, compared mice's levels of activity with samples of urine they left in their cages.
Their findings showed that in healthy mice, as with humans, levels of the protein varied in time with the body clock but in a separate group of mice with disrupted body clocks, the pattern was absent.
Mice which produced higher levels of Cx43 had a greater ability to control their bladders, suggesting that a disrupted body clock could cause the need to visit the lavatory during the night, the researchers said.