How blue light exposure late at night sets you up for disease

Using laptops, cellphones and other devices that give off blue light in the evenings could have serious implications for our health. 

A new paper published by Royal Society Te Apaarangi shows growing exposure to artificial blue light increases the risk of obesity and depression, and potentially some types of cancer.

Watching a laptop or scrolling through your cellphone is a late-night activity used to help wind down, but they are actually disrupting our sleep and research shows that could cause serious problems for our health.

"Long-term sleep disruption can be associated with issues like cardiovascular disease, diabetes, even cancer," said Associate Professor Guy Warman, of Auckland University's Department of Anesthesiology.

Blue light is part of natural daylight, and we need a certain amount of it. The human eye even has a special cell to detect it that helps our brain regulate our internal body clocks.

But screens and artificial lights like LEDs also give it off - and if we get too much at the wrong time, our body gets confused. 

"It effectively adjusts you to a later time zone so it gives you jetlag without travelling," explained Prof Warman.

Too much artificial blue light can also increase the risk of obesity and depression, and weaken our immunity. It doesn't just affect humans, either; it can also interfere with the behaviour and interactions of animals.

"In Africa, they're showing that light pollution - the scattering of light - is influencing how the Milky Way is visible," said Scion Entomology research leader Steve Pawson.

"So dung beetles rolling balls of dung don't know where to roll it because they can't see the Milky Way."

For these reasons, a new paper published by the Royal Society Te Apaarangi is encouraging people to minimise their artificial blue-light use. 

It recommends:

  • Reducing brightness on smartphones, televisions and computers or using night-time settings or apps that lower blue light output.
  • Replacing blue-white lightbulbs, with warmer toned bulbs, and using dimmers in the evening.
  • Being aware of the impact on animals and insects by using outdoor lighting only where needed.

Or of course you can put away blue light devices altogether and wind down the old-fashioned way - with a book instead.