Does light at night pose a health risk?

“Britons should fit blackout blinds and ban electronic gadgets from the bedroom to avert the risk of diseases such as cancer,” the Mail Online warns.

lights on

This alarmist advice is prompted by a review looking at the theory that electrical light at night disrupts our normal body block and could therefore pose a risk to our health.

In the review, researchers looked at various studies, including research linking night-shift work with breast or colon cancer, and light levels in the bedroom being linked to depression and obesity.

As the authors of this review acknowledge, the main problem with this type of evidence is that much of it is circumstantial, and may be influenced by bias and confounding from other factors.

Another drawback is this study does not appear to be systematic. The researchers provide no methods for how they identified the studies they discuss, and we do not know that all relevant studies have been included.

This effectively makes the review an opinion piece, albeit with lashings of supporting evidence. This means there is the risk that the authors have cherry-picked evidence that backs up their claims, while ignoring research that doesn’t fit in with their theories.

The potentially large public health impact of even a small increase in disease risk linked with light at night seems worthy of further study. But this study doesn’t prove that light at night harms our health.

Regardless, getting a good night’s sleep is important.