How did you spend the hour before you went to sleep last night? Were you scrolling through social media, texting your friends and family, or binge-watching your favorite show on Netflix? If so, you consumed blue light before going to sleep. Blue light is a type of light that is found in electronic devices and certain lighting fixtures. A recent study on young-adult males shows that blue light intake before sleep has detrimental health effects. Some of these health effects may include a loss of deep sleep, decreased mental health, and worsened eyesight. Researchers in Japan at Yamagata College of Medical Arts & Sciences Japan and Area of Occupational Therapy focused on determining how blue light affected sleep. Sleep is something everyone values, and it is critical for both short- and long-term well-being. With the growing use of technology in our world, and many lighting companies switching to an LED-style lighting approach, quality sleep is becoming a more concerning health issue due to the negative effect of blue light.
Blue light is a high-energy light that can be seen through human eyes. Blue light can come from the sun, but also comes in the form of electronic devices and LED or fluorescent lighting. In the daytime, blue light has many positive effects such as increasing our memory and helping run our circadian rhythm. The circadian rhythm is the internal body clock, and it helps regulate body temperature, melatonin production, and cognitive performance. When people intake blue light at night it suppresses melatonin release twice as much as other light. This can make it more difficult to go to sleep which can lead to adverse health effects. Blue light at night can disrupt the circadian system. The circadian system is a “cyclical 24-hour period of human biological activity” (Hastings 1995, cited in Wilson 2019). A study showed that 90% of people used blue light in the hour leading up to sleep (Gradisar et al. 2013). With the growing popularity of electronics, the issue has become more prevalent. While research is still lacking, many researchers agree that blue light before sleep brings negative health effects. Previous studies had already shown blue light may increase the likelihood of cancer, obesity, diabetes, etc (Wahl, et al. 2019).
A 2021 study conducted by researchers in Japan attempted to find a direct link to how blue light affects the ratio of deep sleep and sleep quality. These researchers in the Department of Occupational Therapy at Yamagata College of Medical Arts & Sciences in Japan (Ishizawa, et al. 2021) conducted the study independently without the support of corporations or outside investors. The research included the extent a person was exposed to blue light before sleep, and if the participants used methods to help limit the intake of blue light. The researchers recognized the lack of information and knowledge related to sleep and wanted to provide concrete information linking blue light exposure to sleep quality.
The research was performed using eleven college students aged 20-21 who volunteered for the study. People who took medication that may contribute to drowsiness and people with a body mass index over 25 kg/cm^2 were excluded. The experiment took place over a two-week interval of time. Of the eleven people, the group was split into three different groups. Each group was to read for an hour before sleep with a light placed fifty centimeters away from them. The first group received incandescent light (non-blue light). The second group used blue light, and the third group had blue light while wearing blue light-blocking glasses. Over the two weeks, each subject was randomly tested six times. To measure the quality of sleep the researchers used a mat sleep meter (SL- 504; Tanita Corp., Japan) and a portable sleep study system (LS-140; Fukuda Denshi Co. Ltd., Japan). Each subject slept in their own room throughout the study. The results were measured in the morning on six random days and included: the total sleep time, light sleep time, and REM sleep. The data showed no significant difference between the three groups. However, the blue light group had a smaller ratio of deep sleep compared to the other two groups. Body temperature also remained relatively stable for the three groups. Overall, the results were similar throughout the experiment, but there was a significant difference in the ratio of deep sleep. The results of this study showed the effect blue light has on deep sleep. A decreased ratio of deep sleep is linked to many adverse health effects. The disruption of sleep cycles has an impact on mood disorders, the risk of depression, and cognitive dysfunction (Wahl et al. 2019). Not only does a lack of sleep disrupt day-to-day performance, but it also leaves long-lasting irreversible effects. Issues that can arise with a lack of sleep include cardiometabolic dysfunction, diabetes, and obesity (Cauter et al. 2008). Although some may argue the data found in this study is not significant, the results of this study may lead to future research. The initial data found a link that blue light before sleep decreases the ratio of deep sleep and may propel researchers to a more complex study.
The experiment was conducted in a manner that proves the validity of the results. However, there are a few ways that the researchers could have strengthened the findings. First, the group surveyed were male volunteers in the same age range. It would have been better to have randomly selected individuals of different genders and ages. Secondly, the group studied was a small sample. Eleven may not be enough people to have solid data. Even with this, the study was approved by another company and had no outside company pushing an agenda. The results from the study have validity due to the significant statistical difference in the ratio of sleep. To improve a similar study in the future, researchers could randomize the participants to allow for findings that impact different genders and ages. Future researchers could also lengthen the duration of the study by a period of more than two weeks. It is hard to determine long-term changes in a two-week interval.
Additionally, researchers could conduct a broader experiment. Increasing the sample size in the study would help solidify the data. With blue light becoming more prevalent in the day-to-day life of people, it is important to move quickly to understand the true impact of blue lights, including the impact on sleep. A lack of sleep can be detrimental to the human body, and it is important to prevent more damage to the human body. Education on the impact and ways to prevent harm should be made available as soon as possible, i.e. obtaining blue light-blocking glasses as evidenced in the study. Subjects wearing blue-light glasses had a better ratio of deep sleep. Advancing research could potentially decrease both short- and long-term negative effects on people in our world. Sleep is one of the most important activities for the human body. Do you want to know the true effects of scrolling through social media, texting your friends and family, or binge-watching your favorite show on Netflix?
References
Gradisar M, Wolfson A, Harvey G, Hale L, Rosenberg R, Czeisler. 2013. The Sleep and Technology Use of Americans: Findings from the National Sleep Foundation’s 2011 Sleep in America Poll. Journal of Clinical Sleep Medicine. 9(12): 1291–1299. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3836340/. doi.org/10.5664/jcsm.3272
Ishizawa M, Uchiumi T, Takahata M, Yamaki, M, Sata T. 2021. Effects of pre-bedtime blue-light exposure on ratio of deep sleep in healthy young men. Sleep Medicine. 84: 303-307. https://www.sciencedirect.com/science/article/pii/S1389945721003257. doi.org/10.1016/j.sleep.2021.05.046.
Wahl S, Engelhardt M, Schaupp, P, Lappe C, Ivanov I. 2019. The inner clock – blue light sets the human rhythm. J. Biophotonics. 12(12):1-14. https://onlinelibrary.wiley.com/doi/epdf/10.1002/jbio.201900102. doi.org/10.1002/jbio.201900102.
Wilson M. 2019. Artificial blue light and teenagers: Does artificial blue light exposure at night have negative health and wellbeing implications on teenagers? School of Nursing Online Journal. Otago Polytechnic. 6. https://nursingjournal.co.nz/journal/volume-five-2/artificial-blue-light-and-teenagers-does-artificial-blue-light-exposure-at-night-have-negative-health-and-wellbeing-implications-on-teenagers.
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