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Relationship between blue-light protection (BLP) glasses and melatonin, sleep, and circadian rhythm



In recent years, the massive use of electronic devices has led to an increasingly worrying amount of exposure to blue light. Blue light is a type of radiation with a short wavelength in the visible light spectrum, ranging between 450 and 500 nm. This radiation is naturally present in sunlight, which helps regulate our circadian or sleep cycle. Artificially, blue light is strongly emitted by numerous electronic devices, including but not limited to smartphones, tablets, and computers. Due to its relationship with the circadian cycle, blue light can have an adverse influence on our sleep-wake cycle and circadian rhythm.


The circadian cycle is an internal biological clock that regulates the timing of physiological and behavioral processes in living organisms, including sleep. It is a roughly 24-hour cycle that is influenced by external cues such as light and darkness. The circadian cycle is responsible for regulating the timing of sleep and wakefulness, and the quality of sleep has an effect on the circadian cycle. Disruption of the circadian cycle can lead to difficulty falling asleep or staying asleep, which can lead to fatigue, decreased alertness, and other health issues. The relationship between the circadian cycle and sleep is bidirectional, with both influencing each other. Consequently, it is important to maintain a regular sleep-wake cycle to ensure that the circadian cycle is in sync with the external environment.


Research indicates that excessive exposure to blue light at night is linked to several harmful health problems, including sleep disturbances, eye strain, and even heart or reproductive problems. Therefore, it is crucial to take steps to safeguard our health from the potential dangers of excessive blue light exposure.


An effective and well-established method of protecting ourselves from blue light exposure is to wear blue light filtering glasses, commonly known as blue light filter (BLP) lenses. These lenses block blue light from electronic devices and other sources, such as office lamps, which can have a detrimental impact on our sleep-wake cycle and circadian rhythm. Clinical research indicates that BLP lenses can enhance melatonin secretion at night and improve sleep quality without compromising visual quality. However, the use of these optical filters is controversial. The American Academy of Optometry recently published an article stating that it is not advisable to use these types of lenses in children due to the lack of knowledge about the effect of blue light on the development of the eyeball (see Dr. Tosini's article below). Therefore, more research is required to establish the most effective types and levels of blue light filtering for different sleep disorders and individuals.

We recently published a study examining the impact of BLP anti-blue light lenses on melatonin suppression. The study aimed to quantify the efficacy of BLP lenses in reducing the deleterious effects of blue light on melatonin production and the circadian cycle. The study involved measuring the radiant flux from smartphones, calculating retinal illuminance, and measuring the transmittance of blue-light reducing spectacle lenses. We used two types of BLP lenses: tinted and coated. The study found that BLP lenses reduced melatonin suppression by 33%, and that coated lenses were slightly more efficient than tinted BLP lenses. Another part of the study suggests that all smartphones emit strong amounts of short-wavelength light, which may affect the regulation of circadian cycles at night, and that the use of night mode features may be an effective way to mitigate the harmful effects of blue light.


In conclusion, the use of blue light filtering glasses is an effective strategy to protect our health from the potential risks of blue light exposure. By decreasing our exposure to blue light, we can improve the quality and quantity of our sleep, as well as our cognitive function. However, more research is needed to identify the most effective types and levels of blue light filtering for different people and sleep disorders. As we continue to use electronic devices and other sources of blue light, it is imperative to take steps to safeguard our health and well-being.

Emiliano Teran


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