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The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
Only 12 hours after an egg cell is fertilized by a sperm cell, the egg cell starts to divide. As it continues to divide, it moves along the fallopian tube toward the uterus at about 1 inch per day.
More than 150,000 Americans killed by cardiovascular disease are younger than the age of 65 years.
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
About one in five American adults and teenagers have had a genital herpes infection—and most of them don't know it. People with genital herpes have at least twice the risk of becoming infected with HIV if exposed to it than those people who do not have genital herpes.