Why coffee doesn’t give you extra energy: Scientist says pick-me-up is just a ‘loan’ to pay back with sleep
- Caffeine temporarily blocks a chemical called adenosine that prevents drowsiness
- But eventually, adenosine binds to its receptor making us feel drowsy and drowsy
- Dr. Emma Beckett is a molecular nutritionist at Newcastle University
When it comes to waking up, most of us rely on a cup of coffee to give us the kick start we need.
But you don’t actually get extra energy from your flat white, Americano or latte, but according to an expert you borrow it.
Dr. Emma Beckett, a molecular nutritionist from Newcastle University, said this ‘loan’ of feeling awake will eventually have to be paid back with sleep.
She explained that caffeine counteracts drowsiness by temporarily blocking a chemical called adenosine.
This chemical is part of the system that regulates our sleep and wake cycles, with levels rising during the day as it is released as a by-product when energy is used by our cells.

Caffeine prevents drowsiness by temporarily blocking a chemical called adenosine, Dr Emma Beckett, a molecular nutritionist from Newcastle University, wrote on The Conversation website.
Ultimately, adenosine binds to its receptor – part of the cells that receive signals – which tells the cells to slow down, making us feel drowsy and sleepy.
Caffeine can help us wake up by binding to the adenosine receptor and preventing the chemical from causing the drowsy feeling.
“But there’s a catch,” Dr. Beckett wrote on The Conversation’s website. While it feels energizing, this little caffeine intervention is more of a wake-up loan than a creation of new energy.
“This is because the caffeine won’t bind forever and the adenosine it blocks doesn’t go away.”
“So eventually the caffeine breaks down, releases the receptors, and all that adenosine that has been waiting and building up lingers and the sleepy feeling comes back — sometimes all at once.”
“So the debt you owe to the caffeine always has to be paid back eventually, and the only real way to pay it back is sleep.”
Dr. Beckett explained that while we sleep, adenosine levels drop because we expend less energy, meaning we wake up rested in the morning.
Drinking coffee later in the day, when there’s more adenosine in the body, can feel more potent than a morning cup, she said.
And if you like coffee with sugar, it may contribute to the eventual “crash” feeling after a spike in blood sugar, she added.
“Caffeine can be helpful, but it’s not magic,” said Dr. Beckett. “To create energy and to re-energize our bodies, we need enough food, water and sleep.”
The caffeine in tea, energy drinks and other beverages is said to affect the body in a similar way, she wrote.
A recent study found that drinking two to three cups of coffee a day may be linked to longer life.
Researchers found that two to three cups a day were linked to an up to 27 percent lower risk of death compared to those who drank none at all.
The findings, published in the European Journal of Preventive Cardiology, applied to ground, instant and decaffeinated varieties, with researchers saying coffee consumption should be considered part of a healthy lifestyle.
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