From the brains behind brains on, this is the moment of um.

Moment of Um comes to you from 8pm Studios. I'm producer Anna Weggle.

Um, I'm so tired. Like really, really tired. I stayed up way too late reading the most amazing book,

and now my eyelids feel like they weigh a thousand pounds. I would take a nap, but I have so much to do.

Maybe jumping jacks will pet me up. Oh, or a mini dance party.

I'm doing the robot, the wobble. Oh, there's my dog. Come on, let's tango.

That was impressive. I need a seat.

No.

Now I just feel like a sloth again.

Adorable, but so sleepy.

What do I do?

Hmm.

I could just drink a cup of coffee.

I feel better already.

It's like a tiny magic cheerleader cartwheeled into my brain to pep me up.

It kind of makes me wonder how coffee works to keep us awake.

My friend Lily had the same question.

My question is, how does coffee keep you awake? So my name is Maria Cruz and I work as the

dietitian or nutritionist at Williams College in Massachusetts. Coffee has a chemical called

caffeine and caffeine is the chemical that actually keeps us awake and it works through bodies, through the brain and the adrenal glands.

And the way that it works on the brain is by increasing a chemical called serotonin, which

increases our mood. So it's kind of a mood simulator, as well as covering up these little cup-like

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