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Habit stacking: how to anchor a new habit to one you already have

· 6 min read

A stack of matte grey hexagonal blocks with one glowing amber tile on top

“Habit stacking” is the popular name for an old idea from psychology: do the new thing right after something you already do every day. After I pour my coffee, I take my vitamin. After I brush my teeth, I floss. The routine you already have becomes the trigger for the one you want.

It sounds like a productivity trick. It is closer to a description of how habits form in the first place, and the research adds a few details that decide whether a stack holds or quietly falls apart.

Why an existing routine makes a good trigger

Psychologists define a habit as an action that the situation starts for you. Wendy Wood and David Neal describe habits as associations learned slowly between a response and the features of the context it keeps happening in: the place, the time, and the action that came just before. Once the link is strong, noticing the context is enough to start the behaviour, without a goal or a decision in between. (Wood and Neal, 2007)

That last item, “preceding actions”, is the whole basis of stacking. A morning routine is a chain of actions that already run on autopilot. Each one is a reliable, daily, easy to notice event. Putting the new behaviour at a fixed point in that chain gives it the same cue every single time, which is what the association needs.

Benjamin Gardner, Phillippa Lally and Jane Wardle turned this into advice for GPs: pick a simple action, choose a time and place you encounter every day, and repeat the action whenever you meet that cue. They point out that a cue inside an existing daily routine, such as “when I go on my lunch break”, is a convenient and stable starting point. They also note that the usual advice to vary your healthy behaviours to stay interested works against habit formation, because variation depends on motivation and keeps the action from becoming automatic. (Gardner, Lally and Wardle, 2012)

After works better than before

The most useful study on stacking is a small one about dental floss. Gaby Judah and colleagues gave 50 people the same motivational intervention and then split them: half were told to floss before brushing their teeth, half after. Four weeks later, the “after” group tended to have stronger flossing habits. At the eight month follow-up they still had stronger habits and flossed more often. (Judah, Gardner and Aunger, 2013)

The authors point to research on routines: the boundaries between sub-routines work differently from their middles, so where you insert a new step matters. My reading: finishing brushing is a clear “done” moment that can lead straight into the next action, while flossing first means starting with nothing to set it off.

The practical rule: attach the new habit to the end of something, not the start. “After I finish brushing” beats “before I brush”. “When I sit down at my desk after lunch” beats “before lunch”. The anchor should be a completed event you can notice, not a plan to remember something later.

Reminders get you to repeat it, not to automate it

A phone alarm feels like a cue too. It is a different kind. Katarzyna Stawarz, Anna Cox and Ann Blandford ran a four week study comparing reminders with event based cues (doing the action after an existing event). Reminders helped people repeat the behaviour, but they hindered habit development. Event based cues led to higher automaticity. In the same paper they reviewed 115 habit apps and found that most focused on tracking and reminders and offered no support for event based cues. (Stawarz, Cox and Blandford, 2015)

The mechanism is easy to see. If an alarm tells you to stretch, the habit you learn is “stretch when the phone buzzes”. Remove the alarm and nothing is left. If you stretch after you close the laptop at the end of the work day, closing the laptop becomes the trigger, and it happens with or without the phone.

A reminder is still useful as a temporary crutch in week one. Just put the reminder at the anchor (“after you close the laptop”) rather than at a clock time, and plan to drop it.

How to build a stack that holds

1. List anchors you never skip. Write down what you do every day without fail: make coffee, start the car, sit at the desk, brush teeth, plug in the phone at night. An anchor that only happens on weekdays gives you five cues a week, not seven. In Lally’s habit study, each person tied their new behaviour to a single once-daily cue in their own life, such as “after breakfast”. (Lally et al., 2010)

2. Match the location. The new habit should happen where the anchor ends. Vitamins next to the kettle, floss next to the toothbrush, the book on the pillow. If the stack needs you to walk to another room, the chain has a gap where it can break.

3. Write it as one sentence. “After I [anchor], I will [new action].” Use the end of the anchor, keep the new action small enough to finish in two minutes, and keep the wording the same every day.

4. Stack one thing at a time. Each new habit becomes a possible anchor for the next one once it runs on its own. Adding three behaviours to one anchor in the same week gives you three chances to break the chain instead of one.

5. Keep the action identical. Same action, same anchor, same place. Save the variety for after the habit runs without effort.

Tracking the stack

If you track a stacked habit, write the anchor into its name (“floss, after brushing”), so the record reminds you of the cue rather than standing in for it. That works the same on a paper list or in Habit Observer.

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