Children should limit screen time to two hours a day, Japanese health ministry researchers warn

Children should take care not to spend too much of their day sitting down, according to a research team reporting to Japan's health ministry, which identifies long periods on smartphones and other screens as one factor behind sedentary behaviour in the young.

The team, working under the Ministry of Health, Labour and Welfare, warns that sitting for prolonged periods can affect the physical fitness of children and their mental health, including by contributing to low mood. Its advice to parents and carers is practical: parents and children should agree rules together, such as keeping screen time within two hours a day.

Limits on screen time sit at the centre of a wider debate in the UK about how much of childhood should be spent on phones and social media. It runs alongside the UK under-16 social media ban and a growing number of claims over social media addiction in children, and parents looking for practical help can read guidance for parents on children and social media.

Moving more, sitting less

To cut down on uninterrupted sitting, the researchers say it helps if children do not stay seated during breaks at school or at cram school. Activities that can be done upright, such as reading aloud or memorising English vocabulary, are better performed standing, the team suggests.

A central recommendation is that people of all ages, adults included, take regular pauses from sitting. The team gives examples of what these can involve: rising from a chair to stretch, or exercising the feet by lifting and lowering them while remaining seated. It also points to furniture that can be raised so that someone can work at a desk while standing, describing that as one available option.

Advice for older people too

The researchers' findings are not confined to children. Among older people, they say, long periods spent sitting are linked to the development of dementia and to declines in physical function. For that age group, the team recommends frequent interruptions to sitting through everyday activity such as housework, and setting aside time to leave the house.

The guidance places the emphasis on habits families can adopt themselves, with agreed limits on screens and regular movement built into the day, rather than on any single measure. The team presents screen time as one contributor to sedentary behaviour among several, and frames its recommendations as steps that parents and carers can take to reduce the time they spend seated.