spring fever

that's full of energy, vitality

and sexual appetite associated with spring

it's been written about for centuries

but does it really exist?

there's definitely something in this spring time air

a Canadian study showed a way that

teen pregnancy peaks in March

right around spring break

and the another found that men

produce the most

and the healthiest sperm

in early spring

what's causing this seasonal shift?

Scientists think our increase in

energy and better mood

have to do with changes in hormone levels

an important one is melatonin

sometimes called the "sleep hormone"

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

when the nights are longer

we produce more melatonin

and in spring, as the night gets shorter

we produce less of it

may be explaining why we feel

more awake and more active

seratonin is another chemical

that affects our mood

it's known as the "happiness hormone"

and it's level risens in spring time

as it gets sunnier

and the pathologists think that

this changes in hormone levels

may have to do with survival and

reproduction

many animals lay low in the winter

using less energy because food is sacarce

early humans might have done the same

when food became more abundant in the spring

and it make sense that they become...

more....

active

not surprisingly

as you move toward the equator

spring fever disappears

for example

scientists have noticed that seasonal changes

and the birth rates of field mice

flatten out

as you get closer to the equator

but sunshine may not be the only

spring time "pick me up"

for humans, the optimal temperature for

good mood is 72 degree Fahrenheit

and let's face it

once the temperature starts to rise

we're wearing a lot less

for Scientific Americans and Instant Egghead

I'm Yasmin Tayag