National Taiwan University (NTU) researchers have identified the blue light receptors in the human eye that are linked to sleep loss caused by electronic devices.
While the correlation between sleep loss and the use of smartphones and other devices that emit blue light is well known, the mechanism by which the body receives the blue light is not, researchers told an NTU Hospital news conference on Thursday.
In studies on laboratory mice, after eight minutes of exposure to blue light their blood pressure and heart rate increased, their renal sympathetic nerves were activated and they began sweating, NTU professor of biomedical engineering Lin Sung-jan (林頌然) said.
Photo: Wu Liang-yi, Taipei Times
A fivefold increase in sympathetic neural activity was observed after five minutes of exposure to the blue light, he said.
Further research discovered that blue light induces photosensitive retinal ganglion cells — utilized for day-night cycle regulation — to send neural signals to the suprachiasmatic nucleus in the brain, which activates sympathetic nerves throughout the body, he said.
The research confirmed that using blue-light devices before sleeping negatively affects sleep, and potentially causes insomnia and deteriorates eyesight, NTU professor of ophthalmology Chen Ta-ching (陳達慶) said.
Using devices in dimly lit environments aggravates the effects of blue light, because a dilated pupil allows five to six times the normal volume of light to enter the eye, Chen said.
To avoid sleeplessness or deterioration of vision, people should use their electronic devices in well-lit places and enable the night mode setting, he said.
The research also showed that blue light is a stimulant and taking a walk outdoors could boost energy levels and relax the body without straining the eyes, NTU assistant professor of life sciences Chen Shih-kuo (陳示國) said.
The research was published in June in the journal Proceedings of the National Academy of Sciences of United States of America.
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