I’m a devotee of black coffee. I find that Sainsbury’s Continental is the best buy, but it takes about four tablespoonsful per cup to achieve the state of zen-like heightened awareness which allows me to stay awake in meetings.
My problem is that’s it’s very easy to keep drinking the old trimethylxanthine all day: probably not good for various bodily systems, or one’s ‘sleep hygiene’ (to say nothing of the effect on the wallet). Drink enough coffee and your pupils eventually dilate significantly -but exactly how much is enough?
The amount of caffeine per cup varies a lot from source to source. Counting cups isn’t very reliable. Today’s invention is therefore a personal caffeination monitor.
Each paper cup would have attached to the inside, at a uniform height, a small reflective sticker on the surface of which would be imprinted a grid of dots. As the drinker holds the cup to his/her mouth, the reflection of one eye can be seen on this surface and the width of the pupil measured in dots.
This process would be repeated (if necessary on several different cups) these data providing a sign that it’s probably time to have some water and a nice lie down in a dark room.