How to rewire your brain

Rewiring is a figure of speech. Nothing in your head gets unplugged and plugged in somewhere else. What the phrase points at is real, though: a brain that repeats something handles it differently afterwards, and researchers have two ways of seeing that.

One way is to scan people before and after they learn a skill. In healthy adults, weeks of practice have gone with measurable changes in grey matter, the tissue that holds nerve cell bodies, and in white matter, the fibers that link brain areas. The word for this capacity is neuroplasticity, and the page on neuroplasticity exercises goes through the activities that were studied.

The other way is to ask people, day after day, how automatic a new behavior feels. Automatic here means you do it without having to remind yourself or decide. That is the research on habits, and it is the closer match to what most people mean when they say they want to rewire or retrain their brain.

Both kinds of study were done with healthy adults who were learning or practicing something. Neither is about medicine, and this page is not either.

1. Name one change, as something you do. “Stop scrolling at night” gives your brain nothing to repeat. In the words of three habit researchers, it is not possible to form a habit for not doing something (Gardner, Lally and Wardle, 2012). “Read after dinner” can be done, and so it can be repeated.
2. Tie it to a moment that already exists. In the habit study behind the figure at the top of this page, each volunteer chose one behavior to carry out daily in a fixed setting, such as after breakfast. The setting does the reminding, so you do not have to.
3. Keep it hard enough to be learning. When new jugglers were scanned, the change in their brains was not tied to how long they practiced each day or to how good they got (Driemeyer and colleagues, 2008). The authors suggest that learning a new task matters more than drilling one you already know.
4. Repeat on most days, and forgive the miss. In the same habit study, missing one chance to do the behavior made no real difference to how the habit formed. People who did it more consistently followed the expected curve of a growing habit more closely. Aim for most days, and when one is lost, pick it up the next day.
5. Count the hours each week. Trainee taxi drivers who qualified, and whose scans changed, trained about 34.6 hours a week. Those who did not qualify managed about 16.7 (Woollett and Maguire, 2011). Both groups had been training for about as long. The weekly hours were what differed.

A fixed number of days is the claim you will meet most often, and the usual number is 21. It has no study behind it. Three habit researchers traced it to anecdotes about plastic surgery patients, who were said to get used to their new appearance in about that time (Gardner, Lally and Wardle, 2012). Getting used to a face is not the same thing as building a behavior.

When habits were measured day by day, nobody on record finished that fast. The quickest person in the study leveled off after 18 days, and that was the lower edge of the range. The middle was around 66. The study itself lasted 84 days, and the upper end of the range lies well beyond that, so the longest finishes are estimates, worked out from the way each person’s ratings were rising.

The same authors suggest a different thing to tell people: expect a daily habit to take around 10 weeks. That is a planning figure, not a deadline. The harm in a short, fixed number is what happens on the day after it. If the change has not arrived, people decide they have failed, when they are simply partway along. The page on how long a habit takes to form goes deeper into that study.

Stopping is part of the picture, and the studies do not fully agree on what follows. In the second juggling study, volunteers were told to stop after the training weeks and were scanned again 2 and 4 months later. By then the extra grey matter had faded. Most of them could still juggle, though less fluently than before.

Other results held for longer. In the juggling study with a control group, the changes were still present 4 weeks after the last session. And among students who had studied for a major exam, the grey matter increase was still there 3 months afterwards (Draganski and colleagues, 2006).

A fair reading is that the skill tends to outlast the scan result, and that neither is guaranteed without use. If the change you want is a way of spending your evenings, there is no end date after which you can stop doing it. The aim is for it to need less effort, not for it to be over.

How automatic something feels is hard to judge from the inside, and it shifts with the day you just had. Hours and days are easier to check.

A good way to run this test counts both routines from what you already write or say about your day, the new one and the old one. No timer to start and stop. Most journaling apps stop at how the evening felt. They keep the mood, but not the hours that went to the book and to the phone.

One app built for this is Think in Numbers, a smart journaling app with time tracking built in.

You write or say your day in your own words, as it happens or all at once. The app reads what you wrote and counts the hours that went to each part of it: the new routine, the old one it replaces, sleep, work, and the time you never mentioned (shown as unaccounted). Then it shows those hours over days and weeks. Habits keep their streaks, and you can see a weekly target against your real hours.

Write my first day

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The test has two halves on purpose. A new routine that sits on top of the old one has not replaced anything, so the second half checks that the old hours are really falling.

Here are the example person’s four weeks drawn side by side, reading against the phone.

By the fourth week this person read on 7 days and the phone hours had fallen three weeks running. That passes the days half of the test for weeks two, three and four. One more such week completes it, and after that the count simply goes on.

Each figure above links to one of these papers. Our notes on each one record whether it was read in full or as an abstract.

1. Lally, P., van Jaarsveld, C. H. M., Potts, H. W. W. and Wardle, J. (2010). How are habits formed: Modelling habit formation in the real world. European Journal of Social Psychology, 40(6), 998 to 1009.
2. Gardner, B., Lally, P. and Wardle, J. (2012). Making health habitual: the psychology of 'habit-formation' and general practice. British Journal of General Practice, 62(605), 664 to 666.
3. Driemeyer, J., Boyke, J., Gaser, C., Büchel, C. and May, A. (2008). Changes in gray matter induced by learning, revisited. PLoS ONE, 3(7), e2669.
4. Woollett, K. and Maguire, E. A. (2011). Acquiring “the Knowledge” of London’s layout drives structural brain changes. Current Biology, 21(24), 2109 to 2114.
5. Lappe, C., Herholz, S. C., Trainor, L. J. and Pantev, C. (2008). Cortical plasticity induced by short-term unimodal and multimodal musical training. Journal of Neuroscience, 28(39), 9632 to 9639.
6. Scholz, J., Klein, M. C., Behrens, T. E. J. and Johansen-Berg, H. (2009). Training induces changes in white-matter architecture. Nature Neuroscience, 12(11), 1370 to 1371.
7. Mårtensson, J., Eriksson, J., Bodammer, N. C., Lindgren, M., Johansson, M., Nyberg, L. and Lövdén, M. (2012). Growth of language-related brain areas after foreign language learning. NeuroImage, 63(1), 240 to 244.
8. Draganski, B., Gaser, C., Busch, V., Schuierer, G., Bogdahn, U. and May, A. (2004). Neuroplasticity: Changes in grey matter induced by training. Nature, 427(6972), 311 to 312.
9. Draganski, B., Gaser, C., Kempermann, G., Kuhn, H. G., Winkler, J., Büchel, C. and May, A. (2006). Temporal and spatial dynamics of brain structure changes during extensive learning. Journal of Neuroscience, 26(23), 6314 to 6317.
10. Owen, A. M., Hampshire, A., Grahn, J. A., Stenton, R., Dajani, S., Burns, A. S., Howard, R. J. and Ballard, C. G. (2010). Putting brain training to the test. Nature, 465(7299), 775 to 778.