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The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
About 600,000 particles of skin are shed every hour by each human. If you live to age 70 years, you have shed 105 pounds of dead skin.
Side effects from substance abuse include nausea, dehydration, reduced productivitiy, and dependence. Though these effects usually worsen over time, the constant need for the substance often overcomes rational thinking.
Russia has the highest death rate from cardiovascular disease followed by the Ukraine, Romania, Hungary, and Poland.
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.
![The skeleton of a dwarf elephant from the island of Crete. Dwarf elephants were present on some Medi](https://biology-forums.com/gallery/47/medium_27692_23_04_12_3_17_40.jpeg)
![This 1900 photograph of steel factories at night in Duquesne, near Pittsburgh, was tinted by hand. S](https://biology-forums.com/gallery/47/medium_27_24_08_15_1_27_03_22383854.jpeg)