Our nights are now more brightly lit than ever before.
As countries all over the world, including New Zealand, busily replace yellow high-pressure sodium street lights with cheaper, more energy-efficient, white LED lamps they're going to get even brighter.
But could all this street lighting at night be harming our health?
A growing body of research links high levels of artificial light with a host of health problems.
Previous studies have linked a lot of light at night to obesity, diabetes, depression and reproductive problems, as well as disruptions to animal life. And last June the American Medical Association highlighted the health consequences caused by poor sleep that it blamed on the accelerating move towards LED street lighting in the US.
At the heart of all these concerns is the way that brighter street lights seem to interfere with our sleep patterns and the production of the hormone melatonin, which is produced in the pineal gland in our brain and can also be taken as a supplement. Melatonin plays an important role in regulating our sleep and is also believed to have anti-cancer properties.
Peter James at Harvard Medical School has just used information gathered from more than 100,000 nurses living across the US to map elevated night-time light levels with increased breast cancer risk.
Meanwhile, Professor Richard Stevens conducted similar studies last year looking at light levels and breast cancer risk in Connecticut, since first becoming interested in the issue more than 20 years ago.
He's recently written about the potential link between outdoor artificial light levels and breast cancer rates in The Conversation.