What is blue light?
Sunlight is made up of red, orange, yellow, green, blue, indigo and violet light. When combined, it becomes the white light we see. Each of these has a different energy and wavelength. Rays on the red end have longer wavelengths and less energy. On the other end, blue rays have shorter wavelengths and more energy. Light that looks white can have a large blue component, which can expose the eye to a higher amount of wavelength from the blue end of the spectrum.
The largest source of blue light is sunlight. In addition, there are many other sources:
- Fluorescent light
- CFL (compact fluorescent light) bulbs
- LED light
- Flat screen LED televisions
- Computer monitors, smart phones, and tablet screens
Blue light exposure you receive from screens is small compared to the amount of exposure from the sun. And yet, there is concern over the long-term effects of screen exposure because of the close proximity of the screens and the length of time spent looking at them. According to a recent NEI-funded study, children’s eyes absorb more blue light than adults from digital device screens.
How does blue light affect my health?
Deep, restful sleep is essential for allowing your mind and body to heal, recuperate, and recover from the stress and exhaustion of the day.
Blue light impacts photoreceptor cells in your eyes and suppresses the natural production of the sleep hormone melatonin, which throws off your body’s internal clock, disrupting your ability to sleep deeply and restfully. Blue light also emits a unique glare that impacts your retina causing eye strain, headaches, and physical and mental fatigue.
Blue light may contribute to and/or be linked to many chronic health conditions, including but not limited to:
- Eye strain
- Short-term memory loss
- Problems sleeping, due to melatonin suppression
- Stress and anxiety, due to cortisol suppression
- Symptoms of Seasonal Affective Disorder or depression
- Endocrine disruption and a poor immune system
- Female hormonal/menstrual cycle disruption
- Weight issues
- Agoraphobia (anxiety disorder)
Does wearing blue light blocking glasses at night really improve sleep?
In a 2009 study, researchers investigated whether wearing blue light blocking glasses three hours before sleep would help insomniacs who had difficulty falling asleep or maintaining sleep to improve their sleep. They compared amber glasses that completely blocked wavelengths < 525 nm and around 50% at 550 nm with clear glasses that only blocked UV light. Participants completed sleep diaries for one week before wearing the glasses and for two weeks while they were wearing the glasses. The group wearing the blue-blockers experienced significantly improved sleep and mood. [link to study]
In a 2017 study, researchers had insomniacs wear either amber-colored glasses that filter about 65% of blue light or clear glasses for two hours before bedtime. In this study, all participants had to undergo both conditions. In a questionnaire preceding the experiment, participants reported unrefreshing sleep, difficulty staying asleep, difficulty falling asleep, and frequent awakenings. While glasses were off during sleep, the participants were instructed to put them on before using any light or electronic device at night. Total sleep time and sleep quality were significantly improved when participants wore amber glasses. [link to study]
How do I use blue light blocking glasses during the day?
Blue Free day Lenses are for anyone who spends time indoors in artificial light during the day, especially students, employees, office workers, hospital workers, video gamers, and anyone who works on a computer screen or uses screen devices. Our day lenses reduce the most damaging blue light emission from LED lighting, fluorescent lighting, and screen devices, by approximately 42%. This reduction balances out the color spectrum found in artificial lighting, rendering it far less harmful, protecting your eyesight and light-driven hormones, such as cortisol and melatonin, from damage.
How do I use blue light blocking glasses at night?
When the sun sets, put on your blue-blocking night glasses. For best results wear them consistently from sunset until sleep. If you get up at night and use light, be sure to wear your glasses or change the lighting in your house to utilize only natural light during the day, and red incandescent bulbs at night. Even brief exposure to artificial can disrupt our internal clock. If you wake before sunrise, be sure to wear your night glasses until sunrise.
Are there studies showing that blue light is harmful?
The science behind blue light and its effects on your body is well-established. The following is a non-comprehensive list of studies demonstrating the effects of blue light.
- Blue-Light Filtering Spectacle Lenses: Optical and Clinical Performances
- Melanopsin Regulates Both Sleep-Promoting and Arousal-Promoting Responses to Light
- Artificial Outdoor Nighttime Lights Associate with Altered Sleep Behavior in the American General Population
- How Light Affects Our Sleep
- Measuring and using light in the melanopsin age
- Morning and Evening Blue-Enriched Light Exposure Alters Metabolic Function in Normal Weight Adults
- Spectral responses of the human circadian system depend on the irradiance and duration of exposure to light
- Green light attenuates melatonin output and sleepiness during sleep deprivation
- Extent and Health Consequences of Chronic Sleep Loss and Sleep Disorders
- Circadian Rhythm and Human Health
- Light-at-night-induced circadian disruption, cancer and aging
- Blue-blocking Glasses To Improve Sleep And ADHD Symptoms Developed
- Artificial light at night could increase the risk of type 2 diabetes and other diseases
- Circadian Rhythm Disturbances in Patients with Alzheimer's Disease: A Review
- Sleep and circadian rhythm disruption in psychiatric and neurodegenerative disease