Caffeine, sleep, and the drive home.

22:00 has 80 mg, 01:00 has 50, 03:00 has 40, 05:00 has 30, and 07:00 has none. For scale, a glass of çay is about 20 mg and a single espresso roughly 60–80.

Because the next thing you do after a night shift is go home and sleep. Anything you drink at seven is still largely in you at eight. So the last can of the shift is apricot and linden and nothing else.

It is not nothing; it is about one glass of çay. Most people sleep with that in them; some notice it. The calculator lets you set your own bedtime and half-life, and you can pick an earlier can to leave less.

They add up. Two cans at their own hours leave about 40 mg at 08:00. The calculator will show you any combination; the range is built for one can a shift.

The European Food Safety Authority advises up to 200 mg of caffeine a day during pregnancy and breast-feeding, and caffeine clears far more slowly in pregnancy, so the dose rule does not hold. Ask your doctor or midwife. Three of the cans carry the EU high-caffeine wording for this reason.

No.

Some medicines change how fast caffeine is cleared, and some conditions make it a bad idea. Ask your doctor before drinking any caffeinated drink regularly.

Please do not. Caffeine hides how drunk you are without making you less drunk.

No. Caffeine can make you feel more alert than you are. If you are too tired to drive, take a taxi, the ferry, or a nap first.

No added sugar and no sweeteners. Each can has 3–4 g of sugars that come with the fruit juice, which is why it is sharp rather than sweet.

No. Caffeine is the only active ingredient, and the can says how much.

They are the bare aluminium, left unprinted. It saves ink and it catches the light when the can turns.

In the NÖBET cooler outside twelve all-night kiosks in Istanbul — or you could, if the company existed.

No. It is a design study: the company, the kiosks, the prices and the cans are invented. The caffeine arithmetic is real, and computed on the page from a standard model.