Coffee may perk up people, but it puts water to sleep.

New research published in the Journal of Physics Communication found that both caffeine (C₈H₁₀N₄O₂) and taurine (C₂H₇NO₃S), a common additive in energy drinks, actually slows the rotation of surrounding water molecules.

The effect is negligible for human health — researchers estimate that the caffeine in a cup of coffee slows about one in a million water molecules in the body, according to Physics Today.

However, the findings could be relevant in the study of emulsions, hydrogels, and similar substances.

Learn more about the study – and the science.

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• NCA Guide to Caffeine and Health
• The Challenges of Measuring Caffeine Levels
• Is Caffeine In Your Genes?
• Caffeine in Context