We as are humans are constantly surrounded by light—whether it's from a cell phone screen, TV, working on a computer late at night, or the lights in our homes—and research suggests that this has a negative impact on our health. The negative side effects to our health include the loss of muscle and bone mass, an inflamed immune system, and osteoporosis.
The study was conducted by neuroscientist Johanna Meijer from Leiden University Medical Centre in the Netherlands on 130 mice. These mice were exposed to constant light for six months, and the results were startling. These mice showed adverse health deterioration that is often associated with stress and pathogens. So while these findings haven't been studied on humans, the constant light exposure to mice shows that it essentially speeds up the aging process.
While this all sounds pretty formidable, there is some good news. The good news is that these adverse side effects are not permanent and can be reversed. The study showed that if the mice's circadian day/night rhythms were restored, the negative health effects were in fact eliminated.
It took approximately two weeks of regular day/night sleep rhythms before the negative side effects began to subside. That shows how dangerous it can be for those people who work odd shift hours, or for those who stay up late at night on their electronic devices and are exposed to light.
We seem to be most optimized to live within a set day/night rhythm, but ironically, we are becoming more and more deprived of this as our lives become increasingly illuminated. Not only is it adversely affecting our health, but it's also drawing us away from nature's seasonal cycles. This renders us vulnerable to mortality and morbidity.
Even when we turn off our lights to sleep at night, we are often surrounded by ambient lighting—whether it be from a digital clock or light coming in from a city skyline. And what about the people who simply cannot escape from light, such as those staying in hospitals or living in nursing homes? Based on this research, it seems that we should pay close attention to light exposure and possibly monitor it because having set light and dark cycles in our lives does matter.