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Estimate your daily blue light exposure from screens, understand eyeâstrain and sleepâdisruption risk, and get simple changes that protect your eyes and circadian rhythm.
Digital screens emit high-energy visible (HEV) blue light with wavelengths between 400-495 nanometers. While blue light exposure during the day helps regulate your circadian rhythm and keeps you alert, excessive exposureâespecially in the eveningâcan have significant effects on both your eyes and your sleep.
This calculator evaluates your screen time patterns, brightness levels, viewing distance, and protective habits to estimate your risk for digital eye strain and sleep disruption. Understanding your blue light exposure helps you make informed decisions about screen habits.
Every 20 minutes, look at something 20 feet away for at least 20 seconds. This simple practice reduces eye strain by allowing your eye muscles to relax and your blink rate to normalize. Set a timer to remind yourself!
Digital eye strain (also called computer vision syndrome) affects 50-90% of people who work at screens. Symptoms include:
The most significant impact of evening blue light exposure is on your sleep. Here's how it works:
Your body produces melatonin, the "sleep hormone," when it senses darkness. Blue light in the 460-480 nm range is particularly effective at suppressing melatonin production because it signals "daytime" to your brain. Even small amounts of blue light in the 2 hours before bed can:
Research shows that just 2 hours of tablet use before bed can suppress melatonin by 22%. Using a phone in bed with the screen close to your face can be even more impactful. This is why evening screen time is weighted heavily in our calculatorâit's the single most important factor for sleep quality.
Our calculator evaluates four key factors that influence your blue light exposure and its effects:
More hours in front of screens means more cumulative light exposure and more time for eye strain to develop. While there's no magic "safe" number, most eye specialists recommend limiting recreational screen time and taking frequent breaks during work use.
Screen use in the 2-3 hours before bedtime has outsized effects on sleep. The closer to bedtime, the more disruptive. Using screens in bed with the room dark is particularly problematicâthe contrast makes the light more impactful.
Brighter screens and closer viewing distances increase the intensity of light reaching your retinas. High brightness in a dark room is especially straining. Viewing distance matters tooâphones held close to your face deliver more concentrated light than a TV across the room.
Blue light filters (night mode), regular breaks, and proper screen positioning can significantly reduce your risk. These habits don't eliminate blue light exposure but can reduce its impact substantially.
Several strategies can reduce blue light exposure and its effects:
Built-in features like Night Shift (iOS), Night Light (Windows), and f.lux shift screen colors toward warmer tones in the evening, reducing blue light emission. These are free, effective, and should be enabled on all your devices.
Blue-blocking glasses filter some blue light before it reaches your eyes. Research shows mixed resultsâthey may help some people but aren't a substitute for good screen habits. They're most useful for people who can't reduce evening screen time.
Blue light filtering screen protectors can reduce blue light emission from specific devices. Quality varies significantly by brand and product.
Proper room lighting (avoid using screens in complete darkness), larger text sizes (to increase viewing distance), and monitor positioning all contribute to reduced strain.
Children's eyes are particularly susceptible to blue light effects because:
The American Academy of Pediatrics recommends limiting screen time for children and especially avoiding screens in the hour before bedtime.
Current research mainly links screen blue light to eye strain and sleep disruption, not to permanent retinal damage at typical use levels. Some lab studies show blue light can damage retinal cells, but these use much higher intensities than screens emit. However, the long-term effects of decades of heavy screen use are not yet fully understood, so good screen hygiene remains important.
Using bright screens in the last 1-2 hours before bed can significantly delay melatonin release and make it harder to fall asleep. Most sleep experts recommend keeping screens dim, using warm filters, or avoiding them altogether in that window. The closer to bedtime and the brighter the screen, the more disruptive the effect.
Blue-blocking glasses may reduce some blue light reaching your eyes and might help some people with eye strain or sleep. However, research shows mixed results, and they don't fix underlying issues like excessive screen time, close viewing, or lack of breaks. Think of them as one tool alongside good screen hygiene, not a magic solution.
No. Blue light during the day is actually beneficialâit helps regulate your circadian rhythm, boosts alertness, and improves mood. The issue is specifically excessive blue light in the evening, which interferes with natural melatonin production and sleep timing. Morning blue light exposure (including natural sunlight) is good for you.
Dark mode reduces overall screen brightness, which can reduce eye strain and total light exposure. However, it doesn't specifically reduce the blue wavelengthsâyou'll still want night mode/warm filter features for that. Dark mode is most helpful for reducing strain in low-light environments.
E-ink devices (like Kindle Paperwhite) emit much less light than tablets and phones, making them a better choice for evening reading. Front-lit e-readers with warm light settings are especially good. However, backlit tablets and phones with warm filters enabled and low brightness are a reasonable alternative.
Children's eyes let in more blue light than adults' (larger pupils, more transparent lenses), and their circadian rhythms are more sensitive to disruption. This makes limiting evening screen time especially important for children. The American Academy of Pediatrics recommends avoiding screens in the hour before bedtime for all children.
Blue light itself may not directly cause headaches, but digital eye strain from prolonged screen use often does. Eye muscle fatigue, reduced blinking, poor posture, and screen glare all contribute to screen-related headaches. Following the 20-20-20 rule and proper screen positioning can help.