• A 48-week study of mice found that artificial light prematurely ages them
• The light disrupts the body’s natural day/night rhythm cycle
• Mice experienced muscle-weakness and bone-density loss
• Has implications for shift workers who may face similar health risks
Many people work in offices with harsh lighting or work late shifts, but what if the artificial light has a direct impact on your health?
A 48-week study by neuroscientists has found that mice exposed to artificial light prematurely experienced age-related ailments.
If it affects people the same way as mice then it has serious health implications for people who work late under artificial light.
Researchers at Leiden University Medical Center in the Netherlands decided to explore the relationship between artificial light and mice, to see if it disrupts the body clock and the negative physiological repercussions of this. Over a period of 24-weeks lab mice were exposed to continuous light and their health was monitored.
All living creatures including animals, humans and plants have circadian rhythms which are biological patterns of behaviour that repeat every 24 hours. These can include secreting melatonin and testosterone, raising and lowering of body temperature and deep sleep.
The study found that the pervasive use of light, especially during normal sleeping hours, affected the circadian rhythm of the mice which had detrimental repercussions on their health. The mice showed early signs of osteoporosis, they had less forelimb grip strength and were not able to hang from wires as long as they normally could. Additionally they suffered from inflamed muscles. All traditionally symptoms of aging.
After 24 weeks the mice were returned to a regular day/night light whereby the artificial light was turned off for part of their day. The mice’s circadian rhythm returned to near normal and their health problems subsided.
This is compelling evidence that over-exposure to artificial lighting during traditional sleeping hours can affect circadian rhythm and leave one prone to disease.
Johanna Meijer is a neuroscientist who was part of the Leiden University Medical Centre study of mice. Speaking to Nature she said “We came to know that smoking was bad, or that sugar is bad, but light was never an issue,” says Meijer. “Light and darkness matter.”
This is compelling evidence that over-exposure to artificial lighting during traditional sleeping hours can affect circadian rhythm and leave mice prone to disease. Whilst more studies are required before drawing similar conclusions for people, it can make us more conscientious of how the elderly or sick are treated. People in nursing homes and patients in hospitals might be exposed to artificial light at night from a nearby hallway and cleaners who work night shifts are exposed to the constant glare of office lights. A better awareness of this can lead to reducing light levels at night.