How new habits stick

The first week of any change to your evenings tends to feel like effort. You have to remember to dim the lights, and then decide all over again that tonight the phone goes down. It's easy to read that effort as a sign the change isn't working, when it's simply the stage every new routine goes through before it runs on its own.

How a routine becomes automatic

Psychologists describe a habit as a learned link between a situation and an action. Wood and Neal (2007), reviewing the research, set out how it forms: each time you do the same thing in the same setting, or straight after the same step, the brain strengthens the association between the two. Once it's strong enough, the setting itself triggers the action, and you no longer need to hold the goal in mind for it to happen. They also describe these links as building slowly and as hard to shift with the odd occasion when you do something different, which matters when you miss a night.

That's why we tie each change in your plan to something that already happens every evening. The cue is the thing doing the remembering, so it has to be reliable.

Weeks, sometimes months

Lally and colleagues (2010) followed 96 volunteers who each chose one new eating, drinking or activity habit and carried it out daily in the same setting, for example "after breakfast", for 12 weeks. Every day they rated how automatic it felt. For the people whose progress the researchers could chart, the time to get close to their own ceiling of automaticity ranged from 18 to 254 days. Some of that range was projected beyond the 12 weeks of the study, and these weren't sleep habits, so we treat the figures as a sense of scale rather than a timetable. People who carried out the behaviour more consistently showed progress that followed the expected curve more closely, and, most usefully here, missing a single day made no real difference to the process.

Planning the moment in advance

An if-then plan, which psychologists call an implementation intention, decides in advance exactly when and where you'll act: "If I've brushed my teeth, then I put my phone on charge in the kitchen." The plan links the cue to the action before the moment arrives, so you don't have to decide again each evening, tired, at the end of the day.

Loft and Cameron (2013) tested this with sleep. They randomly assigned 104 business employees to one of four short mental-imagery exercises, practised daily for 21 days: picturing if-then plans for their sleep habits, imagery designed to wind them down, both together, or a neutral control. The people who practised if-then plans reported bigger improvements in their sleep habits, their sleep quality and how quickly they fell asleep than those using the wind-down imagery or the control exercise. The results were self-reported and it's a single trial, so we'd call it promising rather than settled.

Building it into your plan

Your plan gives you one or two changes at a time, each written as an if-then plan tied to something you already do, and your diary records whether it happened. The first fortnight will feel deliberate. That's expected, and it's the stage when the link is being built.

If you miss a night, pick it up the next. Lally's findings give no reason to think a single missed day sends you back to the start, and the plan is built the same way: when we review progress at week six, a change counts as held if you managed it on at least 10 of 14 nights, and one lapse doesn't reset your progress. If a change keeps slipping, that tells us the cue isn't reliable enough, and we'll look for a better one rather than asking you to try harder.