Blue light

🗒️ Description

Blue light is the high-energy visible (HEV) light emitted by screens, LEDs, and the sun. Excessive exposure, especially in the evening, suppresses melatonin production and disrupts the circadian rhythm, leading to poor sleep quality.

🧩 Key facts:

• Blue light wavelength: 380-500 nm
• Highest exposure sources: smartphones, monitors, LED lighting
• Evening exposure (2-3h before sleep) has the strongest negative effect on sleep
• Kindle uses e-ink which doesn’t emit blue light — better for reading before bed
• Windows Night Light and similar filters reduce blue light from screens

📖 Further reading

Blue light has a dark side - Harvard Health

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