Before you start

This is a short book and you can read it in two or three sittings. It's about one habit. You drink coffee, or tea, or something with caffeine in it, to get through the day. The first cup is the one you can't do without. The second is the one at three, when the afternoon goes flat. There may be a third around five, to get you home. Then at eleven you're in bed and awake, and at half past six the alarm goes, and you're tired, and you have a coffee.

I'm going to argue three things. The first is that this makes sense from the inside. The cup does make you feel better, at once, every time, and it's pleasant, cheap and everywhere. The second is that most of what the cup gives you is the removal of something the previous cup caused. A regular drinker who's had their morning coffee is roughly as alert as someone who never drinks it. They aren't ahead. They've got back to level. What the afternoon cup takes away is a low that the morning cups helped to make, and what all of them take from the night is real and mostly invisible to you. The third is practical. You count what you actually have, you set a time after which you don't have any, you bring the total down gently over a couple of weeks, and you keep the coffee you like for the reason you like it. Chapters 17 to 20 cover how.

This book doesn't say that coffee is bad for you. The research says the opposite, for most people at ordinary amounts, and chapter 10 sets it out. It doesn't ask you to give up coffee. It asks you to stop using it as a tool for a job it can't do.

Three cautions.

If you're pregnant or breastfeeding, the NHS advises no more than 200 milligrams of caffeine a day, which is roughly two mugs of instant coffee. That's a medical limit and it comes before anything in this book.

If caffeine gives you a racing or irregular heartbeat, or you've been told to limit it because of a heart condition, blood pressure, anxiety, a stomach condition or a medicine you take, follow that advice. The people treating you know your case and I don't.

And if you're exhausted every day despite sleeping seven hours or more, or you snore loudly and stop breathing in your sleep, or your tiredness has come with low mood, weight change or other symptoms, the problem may not be caffeine at all. See a GP before you change anything, and don't let the coffee hide the question.

The notes at the back give my sources and their limits. Where I'm giving my own reasoning and not a finding, I'll say so.