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The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
People who have myopia, or nearsightedness, are not able to see objects at a distance but only up close. It occurs when the cornea is either curved too steeply, the eye is too long, or both. This condition is progressive and worsens with time. More than 100 million people in the United States are nearsighted, but only 20% of those are born with the condition. Diet, eye exercise, drug therapy, and corrective lenses can all help manage nearsightedness.
Vaccines prevent between 2.5 and 4 million deaths every year.
Each year in the United States, there are approximately six million pregnancies. This means that at any one time, about 4% of women in the United States are pregnant.
In the United States, there is a birth every 8 seconds, according to the U.S. Census Bureau's Population Clock.