light and sleep by Yutong Li

Why screen time disrupts sleep

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The back of our eyes contain a sensory membrane called the retina, the innermost layer of which contains a small group of light-sensitive cells that operate like pixels in a digital camera. When these cells are exposed to constant light, a protein called melanopsin is constantly regenerated in them, signalling ambient light levels directly to the brain to regulate consciousness, sleep and alertness. After 10 minutes of light exposure, melanopsin plays a key role in synchronising our biological clocks and, in bright light, suppresses melatonin hormone, the hormone responsible for regulating sleep.

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Circadian Rhythms

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Circadian rhythm is a 24-hour internal clock that coordinates a wide range of processes in the body, including sleep. This rhythm is controlled by a small part of the brain, known as the circadian pacemaker, that is powerfully influenced by light exposure.

Excess or poorly timed artificial light exposure can cause a person’s circadian rhythm to be misaligned with the day-night schedule. This can throw their sleep out-of-whack and induce other concerning health impacts including worsened metabolism, weight gain, cardiovascular problems, and perhaps even an elevated cancer risk Trusted SourceNational Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source . Circadian rhythms are also strongly correlated to mood, mental health, and seasonal affective disorder.

What Types of Light Affect Sleep?

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There can be important differences between types of artificial light as well. Some types have more illuminance and brightness. That said, even light that appears to have the same brightness may, in reality, have a different wavelength, changing how it’s perceived by the eye and brain.

For example, blue light has a short wavelength and is emitted by many LEDs. Studies have found that it has a significantly larger effect on melatonin and circadian rhythm Trusted SourceNational Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source than light with a longer wavelength. Many electronic devices, including cell phones, tablets, and laptops, emit blue light, and their extensive evening use can contribute to sleep problems Trusted SourceNational Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source .

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This article talks about how light at night can affect people's sleep and how, on the other hand, light can also be used as an effective, non-invasive therapeutic option that can improve sleep, mood and overall health

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Examples/Style Reference

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tutorial

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Phototherapy

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Light, natural or artificial, can be used as a therapeutic treatment for physical and/or mental illness. Sunlight has been used therapeutically historically – 3500 years ago for skin lesions by the Egyptians, and in the early 1900s for rickets and tuberculosis. Today, artificial light (lasers and LEDs) is used medically to resolve many conditions such as dermatological diseases, depressive disorders, and neonatal jaundice. Sauna, infrared radiation, also has been shown to have healing properties – improving cardiovascular health, mental wellness, and aiding in detoxification. Thus, light, in many forms, can be used as a tool for healing.

Blue/white light makes us energetic and can interrupt sleep patterns if exposed to around bedtime due to the fact that blue light suppresses melatonin levels. Brain cells tend to be the most sensitive to blue wavelengths and the least sensitive to red wavelengths. Blue wavelengths can even have an impact on those who are blind when it comes to circadian rhythms.

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Red/amber light is the least likely hue of light to impact our internal clocks. Red light in the evening can help improve mental health. This is because red light in the evening helps increase the secretion of melatonin which leads to better sleep at night. Better sleep at night leads to improved cognition and overall mental wellbeing.

Lastly, a May 2016 study found that smartphone use combined with social networking late at night is disrupting the natural circadian rhythms and sleep patterns for people of all ages and nationalities around the globe. Smartphone use during the day obviously leads to excessive screen time, but bedtime use of any digital technology exposes you to more artificial light, throws off your SCN, and exacerbates sleep disturbances. In a statement, lead author of the study Daniel Forger said,

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"Across the board, it appears that society governs bedtime and one's internal clock governs wake time, and a later bedtime is linked to a loss of sleep. At the same time, we found a strong wake-time effect from users' biological clocks—not just their alarm clocks. These findings help to quantify the tug-of-war between solar and social timekeeping."