The circuit before bed
The morning has a mirror, and for many people the mirror is worse. The circuit before bed. Back door, front door, hob, oven, plugs, windows, the straighteners again. Done once, then again from the top because you can't remember the back door, then a third time because the second was rushed. Then bed, and the replay, and sometimes getting up. This chapter is my own suggestion for it, using the methods in chapters 17 and 18.
The circuit has two things that make it harder than the morning. There's no leaving. In the morning, the car is a deadline and it takes you away from the door. At night, the door is fifteen feet from the bed, all night, and the recheck is always available. And the replay has the whole of the dark to run in. Lying still with nothing to do is the perfect condition for going over the back door, and going over it, chapter 5 showed, is a check that fades the memory like any other.
So the circuit needs a firmer once than the morning does. Make a card, or a list on the fridge, with the four or five things on it in the order you meet them on the way to bed. Do the walk once, with the card, saying each item aloud as you do it. "Back door locked. Hob off. Plugs out. Front door locked." Put the card down. That's the once, and the whole circuit is one check, not five, because it was done as one walk with one purpose.
Then go up, and here's the rule. You don't come down. Not to look, not to touch, not to stand at the top of the stairs listening. If the doubt arrives in bed, and in the first week it will, you have the card and you have the sentences, and you reach for those and not for the picture. "I did the circuit. I said each one." That's all the evidence there is, and it's complete.
The replay wants special attention at night, because it's the only recheck available without getting up, and it will present itself as harmless. Notice it starting. "That's a recheck." Turn over, or put the radio on low, or run through something else, the plot of a film, a list of anything. What matters is not to lie there searching the picture of the back door for a detail that will settle it, because the search is the thing that unsettles.
Some people worry that the card makes the circuit into a ritual. I understand the worry, and the difference is in what the card is for. A ritual is done until it feels right. The card is done once, in order, to make the recheck unnecessary, and then it's finished whether it feels right or not. If you find that the card is being done twice, that's the recheck wearing the card's clothes, and the answer is the same as for any recheck. Once, and then bed.
In my expectation, the circuit is the last part of the habit to go quiet, because the night gives the doubt so much room. It does go quiet. The first night you fall asleep without going over the back door, you'll notice in the morning that you slept, and that the house is as you left it, and that's a deposit.