- This is me and I love coffee.
The intoxicating nutty aroma.
The rich chocolatey taste.
Some days I drink three cups
like the average American I am.
Other days, I drink more like five or six.
But is that too much?
First the good news.
It's almost impossible
to overdose on coffee.
There is a lethal dose of
caffeine but it's somewhere
around 10 grams and the average cup of Joe
has around 100 milligrams.
You'd likely have to drink 100 cups
in rapid succession to OD.
But that's not to say there's
no such thing as too much.
The FDA recommends no more
than four to five cups a day
for the average healthy adult.
More than that and you
might start to experience
some nasty side effects.
- Most people take in coffee to increase
their focus and concentration
but once you take in too much
you start to lose that focus
People start getting
more agitated, irritable.
Narrator: That's thanks to
the hormone, adrenaline.
When caffeine hits your
system it stimulates your
adrenal glands which release
the hormone into your body.
It makes you feel energetic and alert.
Perfect for a fight or flight situation.
But too much can be a bad thing.
Especially if you suffer from anxiety.
- But with anxiety you also
wanna be careful not to
overstimulate or trigger
any sort of panic attacks
and make anxiety worse,
which certainly too much caffeine can do.
- Adrenaline from caffeine
can also increase your heart rate.
That's why doctors also
recommend against drinking coffee
if your heart sometimes beats irregularly.
But the risk is really only
for bonafide coffee junkies.
According to  at least
two observational studies
you have to drink at least
nine cups of coffee a day
to put yourself at risk of arrhythmia.
And finally, there's
the question of sleep.
Coffee's enemy.
Caffeine launches a double
threat on your slumber.
It blocks the neurochemical adenosine
which is what tells your
brain that you're tired.
It releases a cocktail of
stimulants into your brain.
Adrenaline, dopamine, and glutamate.
So after donning your sixth cup of coffee,
you don't just feel
awake but full of energy.
It will power you
through that 2:30 meeting
or the last class of the day.
But if you overdo it,
the effect won't wear off
when it's time for bed.
In one study,
researchers monitored the
sleep of a dozen volunteers.
Some were given a caffeine
pill equivalent to about four
cups of coffee and others
received a placebo instead.
Even when the volunteers
swallowed the caffeine pills
six hours before bedtime, they
spent significantly less time
in the light stages of sleep.
And that can have detrimental
effects on daytime function,
the authors report.
- It's sort of just stuck in this loop
where you're not sleeping
because you drink too much coffee
and then you wake up in the
morning and you're not well
rested and you're drinking more coffee
just to stay awake in the day.
- Sound familiar?
Here's the good news.
If you cut yourself off by 2:00
you typically won't have
trouble falling asleep.
That's because the half-life of caffeine
is around five hours.
And so most of its stimulating effects
will wear off well
before the lights go out.
And if you also limit your
consumption, well then coffee
can actually offer a
number of health benefits.
Research shows that it can help
with everything from memory,
to exercise, to your relationships
with your colleagues.
And that's great because for some of us,
coffee is just something
we'll just never give up.
