Research highlights

Caffeine makes water fall asleep

Contrary to the well-known stimulating effect on humans, caffeine slows down the movement of water molecules. Researchers from the NWO Institute AMOLF in Amsterdam and the ESPCI in Paris report this in a recent publication in the Journal of Physics Communications.

Illustration: Caffeine makes a water molecule (H2O) fall asleep. Credits: I. Cerjak (AMOLF)

A cup of coffee is known for its boosting effect. That is because it contains caffeine: the most commonly used stimulant in the world. It enjoys enormous popularity in beverages like coffee, tea, soft drinks, and energy drinks. Caffeine stimulates the central nervous system and boosts human performance by speeding up reaction times and by increasing alertness.

Caffeine and Energy Drinks
The human body consists for about 60% of water. These water molecules move very fast and continuously create new mutual bonds. Would they show the same behavior in the presence of caffeine? The Dutch researchers asked themselves this question and performed experiments in the laboratory to find out. They used modern laser techniques to study the movement of water molecules and discovered that the presence of caffeine slows down the movement of water molecules by a factor 5. They observed that one caffeine molecule slows down 10 surrounding water molecules. Hence, in a cup of coffee, one in a thousand water molecules is slowed down.

The researchers also studied the effect of taurine, another frequently-used constituent of energy drinks. They discovered that taurine also puts the brake on water molecules; a single molecule of taurine slows down 4 water molecules. Energy drinks often contain both caffeine and taurine. Their combined effect causes 1 in 2000 water molecules to be slowed down.
However, do not worry in case you have just poured yourself a cup of coffee; to notice the effect of slow water, you need to drink so many cups of coffee that it becomes unrealistic. The consumption of one cup of coffee slows down only one in a million water molecules in the human body.

Reference
Wilbert J. Smit, Eliane P. van Dam, Roberto Cota, and Huib J. Bakker, Caffeine and taurine slow down water molecules, Journal of Physics Communications 3, 2019. DOI: 10.1088/2399-6528/ab07e4

Share article
What's happening

Most recent news items

All news items
Natural phenomena ‘hyperuniform disorder’ enables highly efficient, thin silicon solar cells
Research highlights

Natural phenomena ‘hyperuniform disorder’ enables highly efficient, thin silicon solar cells

Silicon solar panels are rigid and heavy, and many rooftops cannot support them. This creates a need for thin, flexible solar cells that can be integrated into building materials. However, making silicon solar cells thinner makes it harder to trap light inside the material. Researchers in the 3D Photovoltaics group found a fascinating way to overcome this challenge using a phenomenon called hyperuniform disorder. They publish their findings in the journal ACS Photonics.

The researchers were able to make highly efficient silicon solar cell materials that are 30 times thinner than conventional ones. They managed to do this by integrating a layer of nanometer sized structures on top of the material. Up close, this pattern looks random, but it is remarkably when you step back: no clumps, no gaps, and no repeating pattern. This is called hyperuniform disorder (or HUD).

Read news item
Off Road grant for a better understanding of intestinal cells that communicate with the immune system
People and recognition

Off Road grant for a better understanding of intestinal cells that communicate with the immune system

AMOLF postdoc Dr. Susanna Eli received an Off Road grant from ZonMw to investigate cells known as M cells in the gut lining that connect the intestine to the immune system. Understanding how M cells develop could ultimately contribute to better treatments for intestinal and immune-related diseases. The grant amounts to 100,000 euros.

Read news item
Science for all ages at Wetenschapsdag 2026
Events and outreach

Science for all ages at Wetenschapsdag 2026

Each year during the national Weekend of Science, AMOLF opens its doors to visitors of all ages to share our enthusiasm for science. AMOLF organizes Wetenschapsdag together with four other research organizations at Amsterdam Science Park: ARCNL, Nikhef, CWI, and University of Amsterdam.

Read news item
About AMOLF

Annual AMOLF Diversity Day focuses on Impostor Phenomenon

Once a year, the AMOLF Inclusion and Diversity team organizes Diversity Day for all AMOLF employees. On October 1, this year’s event took place with the theme Beyond Impostor Phenomenon – More Than Just Luck.

Read news item
Stay informed

Get the latest research highlights, events, and news from our institute delivered to your inbox