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spring fever

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that's full of energy, vitality

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and sexual appetite associated with spring

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it's been written about for centuries

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but does it really exist?

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there's definitely something in this spring time air

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a Canadian study showed a way that

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teen pregnancy peaks in March

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right around spring break

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and another found that men

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produce the most

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and the healthiest sperm

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in early spring

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what's causing this seasonal shift?

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Scientists think our increase in

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energy and better mood

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have to do with changes in hormone levels

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an important one is melatonin

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sometimes called the "sleep hormone"

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it's released at night and helps us to fall asleep

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when the nights are longer

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we produce more melatonin

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and in spring, as the night gets shorter

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we produce less of it

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may be explaining why we feel

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more awake and more active

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seratonin is another chemical

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that affects our mood

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it's known as the "happiness hormone"

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and it's level risens in spring time

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as it gets sunnier

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and the pathologists think that

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this changes in hormone levels

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may have to do with survival and

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reproduction

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many animals lay low in the winter

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using less energy because food is sacarce

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early humans might have done the same

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when food became more abundant in the spring

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and it make sense that they become...

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more....

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active

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not surprisingly

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as you move toward the equator

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spring fever disappears

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for example

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scientists have noticed that seasonal changes

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and the birth rates of field mice

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flatten out

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as you get closer to the equator

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but sunshine may not be the only

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spring time "pick me up"

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for humans, the optimal temperature for

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good mood is 72 degrees Fahrenheit

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and let's face it

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once the temperature starts to rise

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we're wearing a lot less

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for Scientific Americans and Instant Egghead

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I'm Yasmin Tayag