Artificial light may be affecting your health
Turning out the lights is another item that people should consider adding to their list of healthy habits, along with eating right and exercising. A new study showed many negative health consequences for mice kept under conditions of constant light for a period of months.
According to Johanna Meijer of Leiden University Medical Center in the Netherlands, their study showed the importance of the environmental light-dark cycle for health. The absence of these environmental rhythms severely disrupts a wide variety of health parameters, including pro-inflammatory activation of the immune system, muscle loss, and early signs of osteoporosis.
The researchers say that the observed physiological changes were all indicative of “frailty” as is typically seen in people or animals as they age. The good news is these negative health effects are reversible when the environmental light-dark cycle is restored.
They exposed mice to light around the clock for 24 weeks and measured several major health parameters. Their findings revealed that the constant light exposure reduced the normal rhythmic patterns in the brain’s central circadian pacemaker of the suprachiasmatic nuclei (SCN) by 70%.
This disruption also led to a reduction in the animals’ skeletal muscle function. The mice’s bones showed signs of deterioration, and the animals entered a pro-inflammatory state normally observed only in the presence of pathogens or other harmful stimuli. After the mice were returned to a standard light-dark cycle for 2 weeks, the SCN neurons rapidly recovered their normal rhythm, and the animals’ health problems were reversed.
The findings suggest that more care should be taken in considering the amount of light exposure people get, particularly those who are aging or otherwise vulnerable. That’s important given that 75% of the world’s population is exposed to light during the night. Constant light exposure is very common in nursing homes and intensive care units, and many people also work into the night.
The bottom line, according to the researchers is “light exposure matters.”They say they now plan to perform more in-depth analysis of the influence of distorted light-dark cycles on the immune system. They’d also like to investigate possible health benefits to patients exposed to more normal conditions of light and dark.
