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The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
Blood in the urine can be a sign of a kidney stone, glomerulonephritis, or other kidney problems.
Serum cholesterol testing in adults is recommended every 1 to 5 years. People with diabetes and a family history of high cholesterol should be tested even more frequently.
Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.
It is difficult to obtain enough calcium without consuming milk or other dairy foods.