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"Can Dehydration
Affect Our Mood?"

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Water is by far the #1
nutrient in our diet.

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Studies have suggested that
proper hydration may lower

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our risk of heart
disease and cancer,

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and may even make you
a better kisser.

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Brushing artificial skin against
the lips of young women,

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researchers found that
hydrated lips showed

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greater sensitivity
to light touch.

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Although it is well known
that water is essential

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for human survival, only
recently have we begun

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to understand its role in the
maintenance of brain function.

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Makes sense, our
brain is 75% water,

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and so when we get dehydrated
our brain actually shrinks.

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Even mild dehydration,
caused by like exercising

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on a hot day has been shown
to change brain function.

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I’ve talked about the role of
hydration for cognitive function,

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but current findings suggest
that our mood states may also

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be positively influenced
by water consumption.

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The effects of dehydration
in real life

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have not been not
well documented.

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It wasn’t until 2013
when the first study

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to investigate the effects
of mild dehydration

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on a variety of feelings
was published.

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What did
they find?

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The most important effects
of fluid deprivation

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were increased sleepiness
and fatigue,

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lower levels of vigor
and alertness,

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and increased
confusion.

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But as soon as they
gave them some water

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the deleterious effects
on alertness, happiness

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and confusion were
immediately reversed.

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Water absorption actually
happens very rapidly,

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within 5 minutes from
mouth to bloodstream,

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peaking around
minute 20.

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And as an aside, the temperature
of the water appears to matter.

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Which do you think is
absorbed more rapidly:

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cold water, or warm body
temperature water?

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Cold water gets sucked
into the body about 20% faster.

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How can you tell if you’re
dehydrated or not?

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Why don’t you
ask your body?

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If you chugged down some water
and then turned around

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and just peed it
all right out,

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presumably that would be
your body’s way of saying

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Eh, I’m good, all
topped off.

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But if you drank a
bunch of water

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and your body kept
most of it,

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then presumably your
tank was low.

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So these researchers
formalized the technique.

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You empty your bladder,
then chug down

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11ml/kg of body weight,
or 5 ml per pound,

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there’s about
240 ml in a cup,

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so that’s about 3 cups of water, 
you drink 3 cups of water,

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and then an hour later
see how much you pee.

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The empty circles on this
graph up in the corner

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are the dehydrated folks.

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Basically this says that
if you drink three cups

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and pee out
less than 1

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there’s a good chance
you were dehydrated.