Researchers from the United States found that different parts of the brain are responsible for processing data on constant illumination and brief flashes of light. Thus, artificial lighting is more harmful than short flashes of the screen.
The evolution of the human body occurred in a predictable change in light. However, with the spread of electricity, we are increasingly exposed to light at night. In recent years, smartphones with bright screens and the proliferation of social networks that generate dozens of notifications have been aggravating the problem.
In this case, scientists still do not know exactly how artificial lighting affects health, notes Science Daily. To find out, researchers from Northwestern University decided to determine which nerve paths the light passes through in the dark.
Information about light that enters the eye is transmitted to the brain by specialized neurons known as photosensitive retinal ganglion cells (ipRGC). Further, it is processed in the suprachiasmatic nucleus of the hypothalamus, which is responsible for circadian rhythms.
This mechanism synchronizes the biological rhythms of the body, depending on the level of illumination.
The researchers decided to check whether bright flashes of light at an inopportune time could disrupt the operation of this circuit. To do this, they conducted a series of experiments with genetically modified mice, in which the ipRGC neurons transmit information exclusively to the suprachiasmatic nucleus, but not to other areas of the brain. Since mice are nocturnal, prolonged exposure to light causes them to fall asleep.
However, short flashes of light in the experiment did not cause drowsiness in rodents. The body temperature of mice, which is considered an indicator of activity, also did not change.
The team concluded that rodent circadian rhythms were not disturbed. According to scientists, information about bright flashes of light at an inopportune time is not sent to the hypothalamus, but to other areas of the brain that are not associated with the regulation of biological rhythms. This is a logical conclusion, because otherwise the smartphone, switched on once in a night, would sharply shift circadian rhythms.
Now, researchers are only to identify the area of the brain that is responsible for processing data about short-term changes in light.
Thus, if you check notifications on your smartphone, waking up in the middle of the night, it will not break your circadian rhythms. However, warn the authors of the work, the long-term exposure to artificial lighting in the dark can affect the body much more. Long to sit in front of gadgets at night is still not worth it.
According to South Korean scientists, artificial lighting of cities can lead to insomnia. They found that the higher the light pollution in a given area, the more locals buy sleeping pills.