Why can some people drink coffee late at night?

Explore the genetic variants associated with how quickly your body breaks down caffeine.

Caffeine is broken down in the liver by the enzyme CYP1A2, and common genetic variants in and near the gene are associated with how quickly that breakdown happens. That may explain why the same cup of coffee affects people differently.

What the analysis shows

How quickly caffeine is broken down varies between people, and part of that variation is linked to genetic variants — especially in and around the CYP1A2 gene. DNAHelper shows which caffeine-associated variants your raw file carries and what research has linked them to. The result is an association, not a direct measurement of your actual caffeine sensitivity. The analysis runs entirely locally.

Which variants matter

The most studied variant sits near CYP1A2, the gene for the enzyme that clears most of the caffeine you consume. Variants near AHR — a gene that regulates CYP1A2 — have also been linked to caffeine metabolism in large population studies.

What research has actually found

Studies show associations between these variants and both caffeine consumption and measured breakdown speed. But the associations explain only part of the variation — most differences between people come from factors other than these markers.

What matters more than genes

Smoking, pregnancy, certain medications and plain habit affect caffeine clearance as much or more than genetics. Time of day, dose and how tired you are shape how a cup feels — whatever your genotype.

What the result means — and does not mean

The analysis builds on the trait caffeine measurement (moderate evidence strength). The associations are robust but explain only part of the variation. Caffeine sensitivity is strongly shaped by habits, medication and sleep — treat the result as one piece of the puzzle, not a fact.

Associations are statistical — they describe populations, not destinies. Read how we grade evidence in our method.

Privacy: your file never leaves the browser

You choose your raw file locally — it is parsed and analysed entirely in your browser and is not uploaded for the standard analysis. The only exception is the optional DNA Chat feature where you, after explicit consent, can share selected variants. Read the privacy policy · What happens to your DNA file?

Compatible raw files

Works with raw data exports from MyHeritage, 23andMe, AncestryDNA, FamilyTreeDNA (.txt, .csv, .zip). The download guides show exactly where to find your file with each provider — and the file formats are explained here.

Check your caffeine genetics