It makes nine out of 10 people feel better, reduces stress, and may help to keep the body healthy. It's also free, available to almost everyone, and has no known side effects, other than wet tissues, red eyes and runny makeup. Crying may not be a blockbuster drug, but the latest research suggests it's highly effective at healing, and that it improves the mood of 88.8 per cent of weepers, with only 8.4 per cent feeling worse. So beneficial is it that the researchers suggest there may be a case for inducing crying in those who find it difficult to let go.
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But what of crying? Emotional tears come from the same tear glands that produce the fluid that forms a protective film over the eyeballs to keep them free of irritants, and which also releases extra fluid when the eye becomes irritated, or is invaded by a foreign body.
A clue to the purpose of crying may lie in the experimental finding that emotional tears contain different compounds from regular eye watering, such as that triggered by chopping onions.
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Other evidence backs up the theory. It's been shown that tears associated with emotion have higher levels of some proteins, and of manganese and potassium, and hormones, including prolactin than mere eye watering. Manganese is an essential nutrient, and too little can lead to slowed blood clotting, skin problems, and lowered cholesterol levels. Too much can also cause health problems. Potassium is involved in nerve working, muscle control and blood pressure.
Prolactin is a hormone involved in stress and plays a role in the immune system and other body functions. Its involvement in tears may help to explain why women cry more than men. Women have more prolactin than men, and levels rise during pregnancy, when the frequency of crying among women also increases.
There have also been some claims that crying can reduce pain, although there has been little research into this area. The phenomenon, if verified, may be an indirect effect -- in that crying may trigger physical contact with another individual and touch has been linked to improved wellbeing.
http://www.alternet.org/healthwellness/106589/how_crying_can_make_you_healthier/?page=entire