"Everything we already know about fighting off chronic disease, like getting sufficient sleep, staying active throughout life, and having a healthy diet" may stave off premature aging of the immune system, too, Epel said.

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But a product's SPF indicates only its ability to defend against sunburn-causing ultraviolet-B rays and not against ultraviolet-A, which penetrate deeper into the skin and cause premature aging. (Both types contribute to skin cancer.) For example, a person wearing SPF 50 could spend considerable time in the sun without getting burned.

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Today the agency proposed a new requirement that, if finalized, will require warnings on the use of ultraviolet light-emitting tanning beds by individuals under age 18 because of the increased risk of melanoma, squamous cell carcinoma, eye damage, and premature skin aging.

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But Devin had a genetic condition called Hutchinson-Gilford progeria syndrome, also known as progeria, which causes premature, accelerated aging.

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