NTU Discovery: Blue Light Affects Sleep|睡前別玩手機 藍光傷眼.影響睡眠

A National Taiwan University research team has made a major discovery! The team discovered that relatively strong blue light stimulation before going to sleep can not only hurt the eyes, but also activate sympathetic nerves all over the body. This causes excitement and affects normal sleep. In the daytime, blue light stimulation can actually help improve mental alertness. This new research discovery has been published in a well-known science journal in the U.S..


Blue light from smartphones and other devices is harmful to the eyes. According to a new National Taiwan University study, longer-wavelength blue light also stimulates and activates the sympathetic nervous system. In particular, blue light exposure before bed makes it more difficult to fall asleep. This is the first confirmation from the medical community that blue light affects physiological activity.

If you are exposed to extremely strong blue light for one minute, like if you press your eye up against a blue light bulb, your sympathetic nerves may get activated for a long time. Over the long term, this affects sleep.

In lab tests, the research team found that eight minutes of exposure to stronger blue light before sleep activated sympathetic nerves in mice up to 20 times more, leading to a higher heart rate and blood pressure, increased perspiration, and the addition of renal sympathetic nerves and follicle cells. The mice also remained in an excited state for over an hour afterwards.

When sympathetic nerves are stimulated, their interaction with follicle cells is accelerated. This is why sleep follicle stem cells also suddenly get activated.

The study also found that blue light stimulation in the daytime in an office environment can improve mental alertness. Doctors say people should avoid using their phones or looking at screens before bed to protect sleep quality.