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Screentime versus sunshine


Vitamin D, known as the ‘sunshine vitamin’, is the UK’s most popular food supplement according to market research company Mintel: one third of all supplement buyers choose vitamin D. Despite this, vitamin D deficiency affects an estimated 1 billion people worldwide. Our bodies need vitamin D in order to absorb calcium and phosphate, and for maintaining healthy bones, teeth and muscles. Recent evidence even suggests that a vitamin D deficiency can contribute to more severe cases of COVID-19. 


So despite it’s crucial importance and increasingly high demand, a lack of vitamin D remains a global public health issue. Is there anything we can do to increase our vitamin D intake, and avoid a deficiency? Whilst our age, skin colour, and the country we live in all affect our susceptibility to a lack of vitamin D, one factor that we can change (what’s known as a ‘modifiable’ risk factor) is the amount of time we spend indoors away from the sun. Our bodies create vitamin D from direct sunlight when we’re outdoors – it’s synthesised in the skin following exposure to sunlight. Whilst those living near the equator (in Mediterranean and tropical climates) generally get enough sunlight to synthesise sufficient vitamin D all year round, the sun’s UV rays in the UK aren’t strong enough for our bodies to produce adequate vitamin D during the autumn and winter months, the temperate British climate allowing us just over 4 hours of daily sunlight on average. A study by Healthspan UK found that Britons get less than 10 hours of sunlight a week on average during the winter. 


And whilst lousy British weather is definitely to blame, it isn’t the only culprit. The heightened awareness of the danger of the sun’s UV rays, combined with a general lifestyle trend towards an ‘indoor culture’ has driven us to spend more time indoors, on our devices, as opposed to outside in the sunshine. The average Brit spends 22 hours indoors a day; that’s 90% of our time. For children, afternoons that used to be spent playing in the sun have been largely replaced with time indoors, in front of screens – children spend only half as much time playing outside as their parents did. And increased working hours mean many of us spend all daylight hours inside at our desks, confined to computers. In the coronavirus era, where we’re actively encouraged to stay inside, our ‘indoor culture’ has been exacerbated: many of us, especially those without access to a garden, can go days without adequate sunshine.


A study by IOF found that vitamin D deficiency is widespread and on the increase, whilst global internet usage has increased 7-fold since 2000. Coincidence? Maybe, but you don’t need a PhD in statistics to realise the importance of ditching our devices for some allotted ‘sunshine time’ each day.

On the ‘bright side’, we don’t need to spend hours on end basking in the sun to get enough vitamin D - most people can synthesise enough vitamin D by spending short periods of time in the sun everyday. Professor Rhodes from Manchester University suggests that just 9 minutes of lunchtime sunlight each day is enough for Caucasians to keep a vitamin D deficiency at bay throughout the year. Free iOS and Android app ‘Dminder’ helps users figure out how much vitamin D you need a day. 


This article was brought to you by Dig Detox. Our mission is to help people use technology safely because we believe health is your most valuable asset. Please visit for more articles, research and information about the movement.


By Effie Webb

University of Oxford

First Published on 23 May 2020





The Independent

The Guardian

Public Health England



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