Are the screens to blame? In a new, joint study conducted at the University of Haifa and Asuta's sleep laboratory, it was found that exposure to screens that emitted blue light before sleep damaged the quality of sleep, while exposure to screens that emitted "normal" light simulated sleep without exposure to light." Fortunately, there are various apps that filter out the problematic blue spectrum and apply a weak red filter, which reduces the damage to the suppression of the dark hormone melatonin," said Prof. Avraham Haim, one of the study's editors.
The short-wave blue light emitted from the screens we watch is the one that harms the duration and especially the quality of our sleep, according to a new study conducted at the University of Haifa and Assuta's sleep laboratory. It was also found that watching screens that emitted red light did not cause this damage and the sleep was similar to normal sleep. "The light emitted from most screens - computers, smart phones and tablets - is blue light and it harms the body's circulation and our sleep. The solution should be the use of filters that exist today that prevent the emission of this light itself," said Prof. Avraham Haim from the University of Haifa, one of the authors of the study.
Previous studies have already found that watching screens before bed impairs sleep. Other studies have found that exposure to blue light at short wavelengths between 450-500 nm causes damage to the production of melatonin, a hormone that is secreted at night and is associated with normal body circulation and normal sleep. In the current study, published in the journal CHRONOBIOLOGY INTERNATIONAL, the researchers, Prof. Haim from the Department of Human Biology at the University of Haifa along with PhD student Amit Shay Green from the Israeli Center for Interdisciplinary Research in Chronobiology at the University of Haifa and the Sleep and Fatigue Research Institute at the Assuta Medical Center, asked Dr. Merav Cohen-Zion from The School of Behavioral Sciences - Academic Tel Aviv-Jaffa and Prof. Yaron Dagan from the Institute of Applied Chronobiology, Tel Hai Academic College and the Institute for Sleep Research at Assuta Medical Center, to test whether there is a difference in sleep characteristics when exposed to the light of blue versus red screens before going to bed.
19 subjects aged 20-29 who did not know the purpose of the study participated in the study. In the first part of the study, the subjects wore an actigraph for a week (a device that objectively checks the time of falling asleep and the time of awakening), filled out a sleep tracking diary and a sleep habits and sleep quality questionnaire. In the second part of the study, which took place in Assuta's sleep laboratory, the participants were exposed to screens between 21-23 p.m., the hours when the pineal gland begins to produce and secrete the hormone melatonin. The subjects were exposed to four types of lighting: high-intensity blue light, low-intensity blue light, high-intensity red light, and low-intensity red light. After exposure to light, they were connected to devices that read the brain waves and can determine the stages of sleep that the person goes through during the night, including imperceptible awakenings. In the morning, the participants filled out different questionnaires about their feelings.
The results of the study showed that while exposure to red light showed a picture very similar to "normal" sleep, that is, without exposure to light before sleep, exposure to both types of blue light impaired the quality of sleep. It was also found that the exposure to the powerful blue light generally damaged the quality of sleep more, but the effect of the intensity was much smaller than the effect of the type of light - blue or red. That is, the wavelength determines.
For example, on average, exposure to blue light shortened the duration of sleep by about 16 minutes. Also, the exposure to blue light caused a large stoppage of melatonin production, while the exposure to red light showed melatonin production very similar to normal. According to the researchers, the damage to melatonin production indicates a fundamental disruption in the natural mechanisms and in fact in the body's biological clock. For example, it was found that the exposure to blue light caused the body not to carry out the natural mechanism of lowering the body temperature. "Naturally, upon entering sleep, the body begins to lower its temperature, until it reaches its lowest point around 04:00 in the morning, and then when the body reaches the normal temperature again, we wake up. When exposed to red light, the body continued to behave naturally, but the exposure to blue light caused the body to maintain its constant temperature throughout sleep - another evidence of damage to our natural biological clock," said Prof. Haim.
The biological finding that most indicated a sleep disturbance showed that the continuity of sleep after exposure to blue light was most drastically impaired: while after exposure to red light (at both intensities) the people woke up on average 4.5 times (unnoticeable awakenings), after exposure to weak blue light 6.7 awakenings were measured and after Exposure to strong blue light no less than 7.6 awakenings a night. It was not surprising that in the questionnaires they filled out in the morning, the subjects reported that after the exposure to blue light they felt more tired and in a less good mood.
"The exposure to screens during the day in general and at night in particular is an integral part of the world and its intensity will only increase, but in our research we found that it is not the screens that harm our biological clock and therefore our sleep, but the short-wave blue light emitted from them. Fortunately, there are various apps that filter out the problematic blue light in the spectrum and add a weak red filter, which reduces the damage to the suppression of the melatonin hormone," Prof. Haim concluded.
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As a person with a reversed biological clock I am glad I read the article in the hope that I can use the information to improve my situation a little. Thanks.
Especially a night clock must have red digits, otherwise the clock disturbs sleep.