"A coffee after dinner is just civilised"

There's a cup that hasn't come up yet, and for many people it's the one that costs most. The coffee after dinner. The espresso at the end of a meal out. Or, more often and less noticed, the mug of tea at nine on the sofa, made to wind down.

Look at where that cup sits. Dinner is at seven, the coffee at eight, bed at eleven. Three hours. In Drake's study from chapter 7, caffeine three hours before bed disturbed sleep, and caffeine at bedtime disturbed it more. The nine o'clock tea is two hours out. These are the doses that the evidence is least equivocal about, and they're the ones most people never count, because a cup after dinner doesn't feel like caffeine. It feels like the end of the meal.

"To wind down" deserves a look on its own. A mug of tea at nine is warm, familiar and quiet, and everything about the ritual says rest. The contents say the opposite. Seventy-five milligrams of a substance whose job is to block the signal for sleep, taken two hours before you'd like to feel it. People tell me tea relaxes them, and I believe that the ritual does. The caffeine in it is doing what caffeine does, which is the reason you're awake at half past eleven with a mind that won't settle, and blaming the day.

What I'd keep is the ritual, entire. The kettle, the mug, the sofa, the ten minutes. Change what's in the mug. Decaf tea is close enough to tea that most people stop noticing within a week, and there are herbal teas that are pleasant in their own right rather than as substitutes. The after-dinner coffee at home can be decaf and lose nothing that the moment was about, which was sitting down with something warm at the end of the meal.

The restaurant espresso is a separate case. If it's a special evening and you'd like one, have it, and know that you're trading it for a lighter night. That's a fair trade made knowingly, and it's fine. What isn't fine is the same espresso every Friday without noticing that Saturday morning has been foggy for a year.

I'd put the evening cup first on the list of things to change, before anything about the morning. It's the smallest change and the one the night notices soonest. Most people, in my observation, feel the difference within three or four nights.