Artificial light has previously been proven to disrupt the human body clock and hormonal system. A new study shows that artificial light exposure for extended periods of time can also have other adverse effects on health.
A study published in the Cell Press journal Current Biology finds that when mice are exposed to constant artificial lighting for over 5 months, they exhibit many detrimental side effects and a decline in quality of health.
Several of the vital processes and functions of the body follow a natural daily rhythm - the circadian clock - based on 24-hour day-night, light-dark cycles.
Circadian rhythms are controlled by the body’s biological “clock.” There is also a “master clock” in the brain that coordinates all the body clocks so that they are in synch.
The “master clock” consists of a group of nerve cells in the brain called the suprachiasmatic nucleus (SCN), which contains 20,000 neurons and is located deep within the brain in the hypothalamus, medicalnewstoday.com reported.
Circadian rhythms control physical, mental and behavioral changes that follow a 24-hour cycle such as the sleep-wake cycle, body temperature, heart rate, and the release of hormones.
“Our study shows that the environmental light-dark cycle is important for health. We showed that the absence of environmental rhythms leads to severe disruption of a wide variety of health parameters,” said Johanna Meijer, Leiden University Medical Center in the Netherlands.
Health parameters that could be disrupted by a lack of environmental rhythm include pro-inflammatory activation of the immune system, muscle loss, and early signs of osteoporosis.
Tests in the mice revealed that when light and dark patterns were non-existent, and the circadian rhythm disrupted, there was a reduction in skeletal muscle function, bones deteriorated, and pro-inflammatory signs were observed.
Reinstating normal light-dark cycles for a 2-week period stimulated a recovery in the normal rhythmic patterns of the SCN and a reversal of the negative health issues in the mice.
“We used to think of light and darkness as harmless or neutral stimuli with respect to health,” says Meijer. “We now realize this is not the case based on accumulating studies from laboratories all over the world, all pointing in the same direction. Possibly this is not surprising as life evolved under the constant pressure of the light-dark cycle.”
