The problem - called nocturia - which mainly affects the over-60s, leads to disrupted sleep and can significantly affect people's lives.
In a study of more than 300 volunteers, researchers found that reduced salt intake led people to urinate less.
Advice to follow a sensible diet could help improve symptoms, UK doctors said.
The researchers, from Nagasaki University, presented their findings at the European Society of Urology congress in London.