By Dan Satherley
If you think your craving for caffeine in the mornings is because you didn't have enough sleep, you're probably right – but it's not the whole story.
Researchers for the first time have isolated genes believed to be responsible for how much caffeine a person needs to get their desired kick.
In a meta-analysis of several previous studies dating back to 1984, over 47,000 individuals' genes and caffeine intake were looked at, and two genes in particular were linked with higher consumption - ARH and CYP1A2.
According to the research, the CYP1A2 is involved in the breakdown of caffeine in the body, whilst AHR regulates CYP1A2. People with a caffeine-dependent version of CYP1A2 drank, on average, about 38mg more caffeine each day than those without – about the amount found in a can of Coke.
Having a caffeine-friendly AHR gene led people to drink about 44mg more daily.
The study notes that the genes, "together, however, explained between 0.06 and 0.72 percent of the total variation in caffeine intake across studies, suggesting additional variants remain to be discovered".
So perhaps it is just that you didn't have enough sleep.
Click here to read the full report (PDF).
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