Blue Light Exposure Impact Calculator
Find out how much your screens are affecting your sleep. Enter your daily usage.
Hours looking at screens
Your main screen device
Screen time after sunset
What protection do you use
Your age
How well do you sleep
Do you have eye problems
How does blue light affect sleep?
Blue light suppresses melatonin (sleep hormone) by telling your brain it's still daytime. Evening screen use delays sleep onset by 30-60+ minutes. Phones/tablets emit the most (close to eyes); TVs less; monitors intermediate. Even 1-2 hours after sunset affects sleep quality. Blue light filtering helps but doesn't eliminate the effect - total darkness is best for sleep.
Is blue light harmful to eyes?
Blue light isn't causing permanent eye damage in adults, but causes digital eye strain: Dry eyes, headaches, blurry vision, difficulty focusing. Children's eyes absorb more blue light (lens is clearer). Blue light contributes to macular degeneration risk in lab studies but human evidence is inconclusive. The bigger issue is sleep disruption from evening use. Reduce blue light for better sleep and eye comfort.
What actually protects from blue light?
Best protection: 1) No screens 2+ hours before bed. Blue light filters (f.lux, Night Shift) reduce but don't eliminate. Blue light glasses help but quality varies. The 20-20-20 rule: Every 20 min, look 20 feet away for 20 sec. Keep screens at arm's length. Increase screen brightness to match room to reduce pupil constriction. Room lighting also matters - dim screens in bright rooms = more strain.
Do blue light apps actually work?
Yes, but incompletely. Apps like f.lux, Night Shift, and Twilight reduce blue light emission by 40-90%. They help with sleep more than eye strain. Best apps: f.lux (most customizable), Twilight (Android), Apple Night Shift (built-in). They can't block 100% - screen still emits some light. For best sleep, nothing beats no screens before bed. Apps are backup, not solution. Best used with other practices.
How many hours before bed should I stop screens?
Optimal: 2-3 hours before bed for deep sleep. Minimum: 1 hour. Some can get away with 30 min if using blue light filter. It's cumulative - more time = better. If that's impossible, use f.lux + glasses + dim screen + night mode reading. Sleep in complete darkness. The goal is darkness signaling to your brain for natural melatonin release. Any improvement helps, but more is better.