Caffeine is the reason most of us drink coffee in the first place, and the one ingredient of a Fairytale + Grey formula we did not add. The coffee plant makes it to keep insects off its leaves and seeds. We drink it because it is the most widely used substance in the world that changes how awake you feel. Eight of the ten formulas keep it exactly as the bean brought it; the other two have it taken out.
What it is
Caffeine is a small molecule, 1,3,7-trimethylxanthine, drawn here: two fused rings of carbon and nitrogen with three methyl groups on them. It is water-soluble, which is why it is in the cup within the first seconds of brewing, and it crosses from the gut into the blood and from the blood into the brain in less than an hour.
What it does
The brain keeps a kind of tiredness ledger. A molecule called adenosine builds up while you are awake; the longer the day, the more of it sits on its receptors, and the more they signal that it is time to slow down. Caffeine fits the same receptors and does not deliver the message. It does not add energy; it hides, for a while, the signal that you are running out of it. That is the whole trick, and it is why a cup makes you alert rather than nervous when the dose is right.
The effect begins within half an hour and fades over hours, not minutes: the half-life in a healthy adult is about five hours, longer in pregnancy, shorter in smokers. A cup at four in the afternoon is still half there at nine.
How much is in a cup
A cup of filter coffee of 200 ml holds about 90 mg of caffeine; an espresso of 60 ml about 80 mg. A Fairytale + Grey formula brewed from 8 g of ground coffee, or from one capsule, is in the same range, because the base is the same coffee and the actives contribute none.
The European Food Safety Authority, which reviewed every study it could find in 2015, puts the amount that raises no safety concern for healthy adults at 400 mg a day, spread over the day, and at 200 mg in one go: roughly four cups a day, two at a time. In pregnancy the figure is 200 mg a day from all sources. And a single 100 mg close to bedtime, EFSA notes, can make falling asleep take longer for some people: the five-hour half-life, in practice.
The one without it
Baby Shower, OO6, and The Chill, OO9, are decaffeinated. The caffeine is taken out of the green beans before roasting, and what remains is a trace, a few milligrams a cup, less than a tenth of a percent of the bean. Everything else about the coffee is left as it is, which is the point: the ritual without the ledger.
In the formulas
Caffeine is not an active in our sense, and no formula adds it. But it is why the actives are in coffee at all. A vitamin in a jar is taken when you remember; a vitamin in the one cup you never skip is taken every day. Caffeine built that habit long before we did, and we are only riding on it.