What the reliance costs

You may think of the habit as costing a few pounds a week and a slightly dry mouth. I think it costs more, and most of this chapter is my own reckoning. I'll say where a study comes in.

The night. Every night, a little shallower, a little shorter, with less of the deep part. Clark and Landolt's review found that consistently. You don't feel it while it's happening. You feel it at half past six.

The morning shortfall. Every day begins below the level and stays there until the cup. That's an hour or so a day, over years, spent foggy, flat and slightly low, for no reason except yesterday's coffee. Rogers's experiment measured that state. You've been calling it waking up.

The afternoon slump, enlarged. A natural dip with a withdrawal low on top of it. The three o'clock fog is partly made by the half past nine cup.

Never knowing how tired you are. With a signal muffled all day, you can't tell whether you need more sleep, less work, or a holiday. The coffee answers the question before it's asked. This is my own point and I think it's the biggest one. People run years on a shortfall they'd fix in a fortnight if they could feel it.

The tired person. Somewhere along the way you decided you were someone who needs more sleep than they get and can't function without coffee. That belief shapes how you plan, what you take on, and how you think of yourself. It's a description of the habit, not of you.

The jitters and the heart. For some people, caffeine brings a tight chest, a racing heart or a low anxious hum, and in the Bristol work it raised anxiety in people who didn't normally take it. If you've got that hum and you've never connected it with the cups, the count from chapter 11 is worth a look.

Money. Small, but a daily coffee-shop cup is a substantial sum over a year, and it's being bought, on the argument of this book, to fix a problem it causes.

The evening. The half past five cup that gets you home is still in you at eleven, and the settled, drowsy end of the evening that other people get is one you rarely have. You're alert until you're suddenly not.

In return for all that, you've had the pick-up, three or four times a day, and each one has felt like a gift. It was a repayment. That's the trade, laid out. I'd take the other side of it.