How does caffeine keep us awake? - Hanan Qasim
-
0:07 - 0:12Over 100,000 metric tons
of caffeine are consumed -
0:12 - 0:14around the world every year.
-
0:14 - 0:18That's equivalent to the weight
of 14 Eiffel Towers. -
0:18 - 0:21Most of this caffeine is consumed
in coffee and tea, -
0:21 - 0:24but it's also ingested in some sodas,
-
0:24 - 0:25chocolate,
-
0:25 - 0:26caffeine pills,
-
0:26 - 0:29and even beverages labeled decaf.
-
0:29 - 0:33Caffeine helps us feel alert,
focused, happy, and energetic, -
0:33 - 0:36even if we haven't had enough sleep.
-
0:36 - 0:40But it can also raise our blood pressure,
and make us feel anxious. -
0:40 - 0:43It's the world most widely used drug.
-
0:43 - 0:47So how does it keep us awake?
-
0:47 - 0:51Caffeine evolved in plants where
it serves a few purposes. -
0:51 - 0:55In high doses, as it's found in the leaves
and seeds of certain species, -
0:55 - 0:58it's toxic to insects.
-
0:58 - 1:02But when they consume it in lower doses,
as it's found in nectar, -
1:02 - 1:06it can actually help them remember
and revisit flowers. -
1:06 - 1:11In the human body, caffeine acts as a
stimulant for the central nervous system. -
1:11 - 1:16It keeps us awake by blocking one of
the body's key sleep-inducing molecules, -
1:16 - 1:19a substance called adenosine.
-
1:19 - 1:22Your body needs a constant supply
of energy, -
1:22 - 1:27which it gets by breaking down
a high-energy molecule called ATP. -
1:27 - 1:28In the process,
-
1:28 - 1:33it liberates adenosine,
ATP's chemical backbone. -
1:33 - 1:38Neurons in your brain have receptors
perfectly tailored to this molecule. -
1:38 - 1:40When adenosine docks to these receptors,
-
1:40 - 1:44it activates a cascade
of biochemical reactions -
1:44 - 1:46that cause neurons to fire more sluggishly
-
1:46 - 1:50and slow the release of important
brain-signaling molecules. -
1:50 - 1:53In other words, you get sleepy.
-
1:53 - 1:58Caffeine is what's called an adenosine
receptor antagonist. -
1:58 - 2:02That means it derails this process
of slowing your neurons down -
2:02 - 2:04by blocking adenosine receptors.
-
2:04 - 2:09Caffeine and adenosine have a similar
molecular structure, -
2:09 - 2:12close enough that caffeine can wedge into
the adenosine receptors, -
2:12 - 2:15but not close enough to activate them.
-
2:15 - 2:19To summarize,
adenosine inhibits your neurons. -
2:19 - 2:25Caffeine inhibits the inhibitor,
so it stimulates you. -
2:25 - 2:27Caffeine can also boost positive feelings.
-
2:27 - 2:30In some neurons, the adenosine receptors
-
2:30 - 2:34are linked to receptors
for another molecule called dopamine. -
2:34 - 2:39One of dopamine's roles in the brain
is to promote feelings of pleasure. -
2:39 - 2:42When adenosine docks in one of these
paired receptors, -
2:42 - 2:46that can make it harder for dopamine
to fit in its own spot, -
2:46 - 2:49interrupting its mood-lifting work.
-
2:49 - 2:53But when caffeine takes adenosine's place,
it doesn't have the same effect, -
2:53 - 2:56and dopamine can slide in.
-
2:56 - 3:01There's evidence that caffeine's effects
on adenosine and dopamine receptors -
3:01 - 3:05can have long-term benefits, too,
reducing the risk of diseases -
3:05 - 3:10like Parkinson's, Alzheimer's,
and some types of cancer. -
3:10 - 3:15Caffeine can also ramp up the body's
ability to burn fat. -
3:15 - 3:18In fact, some sports organizations think
-
3:18 - 3:21that caffeine gives athletes
an unfair advantage -
3:21 - 3:24and have placed limits on its consumption.
-
3:24 - 3:27From 1972 until 2004,
-
3:27 - 3:32Olympic athletes had to stay below
a certain blood-caffeine concentration -
3:32 - 3:34to compete.
-
3:34 - 3:38Of course, not all of caffeine's effects
are so helpful. -
3:38 - 3:40It might make you feel better
and more alert, -
3:40 - 3:43but it can also raise your heart rate
and blood pressure, -
3:43 - 3:46cause increased urination or diarrhea,
-
3:46 - 3:50and contribute to insomnia and anxiety.
-
3:50 - 3:53Plus, the foods and beverages
caffeine is found in -
3:53 - 3:59have their own impacts on your body
that have to be taken into account. -
3:59 - 4:02Your brain can adapt to regular
consumption of caffeine. -
4:02 - 4:05If your adenosine receptors
are perpetually clogged, -
4:05 - 4:08your body will manufacture extra ones.
-
4:08 - 4:10That way, even with caffeine around,
-
4:10 - 4:15adenosine can still do its job
of signaling the brain to power down. -
4:15 - 4:19That's why you may find you need
to consume more and more caffeine -
4:19 - 4:21to feel as alert.
-
4:21 - 4:24There are more and more adenosine
receptors to block. -
4:24 - 4:27It's also why if you suddenly
quit caffeine, -
4:27 - 4:30you may experience
an unpleasant withdrawal. -
4:30 - 4:32With plenty of receptors
and no competition, -
4:32 - 4:35adenosine can work overtime,
-
4:35 - 4:36causing symptoms like headaches,
-
4:36 - 4:38tiredness,
-
4:38 - 4:40and depressed moods.
-
4:40 - 4:45But in a few days, the extra adenosine
receptors will disappear, -
4:45 - 4:47your body will readjust,
-
4:47 - 4:50and you'll feel just as alert as ever,
-
4:50 - 4:53even without an infusion of the world's
most popular stimulant.
- Title:
- How does caffeine keep us awake? - Hanan Qasim
- Description:
-
View full lesson: http://ed.ted.com/lessons/how-does-caffeine-keep-us-awake-hanan-qasim
Over 100,000 metric tons of caffeine are consumed around the world every year. That’s equivalent to the weight of 14 Eiffel Towers! Caffeine helps us feel alert, focused, and energetic, even if we haven’t had enough sleep — but it can also raise our blood pressure and make us feel anxious. So how does it keep us awake? Hanan Qasim shares the science behind the world’s most widely used drug.
Lesson by Hanan Qasim, animation by Adriatic Animation.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 05:15
Jessica Ruby edited English subtitles for How does caffeine keep us awake? - Hanan Qasim | ||
Jessica Ruby edited English subtitles for How does caffeine keep us awake? - Hanan Qasim | ||
Jennifer Cody edited English subtitles for How does caffeine keep us awake? - Hanan Qasim |