Blue light glasses

What blue light glasses actually change about eye strain and sleep, why the daytime clear lens version and the tinted night version rest on different evidence, and what regular wearers wish they had known before buying a pair.

• Do blue light glasses work? Probably not for eye strain. Maybe for sleep.
• How much difference do blue light glasses make for eye strain or sleep? Probably less than the ads claim.
• What do people who tried blue light glasses wish they'd known first? They help some, not all, and the effect is subtle.

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