Those frequent trips to the bathroom in the middle of the night may be a side effect of a salty diet, say a group of Japanese scientists.

Known as nocturia, the constant need to travel from the bed to the toilet to urinate affects most people over the age of 60, and a distinct number of people younger than that. The team from Nagasaki University has now found that the average number of trips per night correlates to sodium intake, as presented at the 32nd European Association of Urology Congress conference in London this week.

“Night-time urination is a real problem for many people, especially as they get older,” said Matsuo Tomohiro, leader of the scientific team at Nagasaki University. “This work holds out the possibility that a simple dietary modification might significantly improve the quality of life for many people.”

The team looked at 321 people who had relatively high salt intake, and who also had trouble sleeping.

Among this group, some were able to cut their salt intake, and others were unable or even increased their daily sodium diet.

Some 223 of the group reduced their average salt intake from 10.7g per day to 8g per day. Strikingly, the average number of nocturia incidence dropped from 2.3 times each night to 1.4.

On the other end of the spectrum, 98 people increased their salt intake from 9.6g to 11g per day – and their urination trips increased from 2.3 to 2.7 times per night.

The scientists write that the increased salt means more fluid intake during waking hours – as well as potential fluid collection in the tissues, like edema.

But further studies are needed to gauge how effective salt reduction could be in the treatment of the symptoms, they added.

“This is the first study to measure how salt intake affects the frequency of going to the bathroom, so we need to confirm the work with larger studies,” added Tomohiro.

Some estimates hold that nocturia is far more prevalent than traditionally believed. One-third of all adults over 30 get up twice or more in the middle of the night, some experts have said