Statistics with no study attached. The numbers, and where each one came from.
Almost every article about journaling cites the same two or three figures, usually without the study, the sample size, or the year. This page gives each number its source, says how large the effect actually was, and is equally clear about the parts the research does not establish. If you need one line to quote, the honest one is that the effect is real, small, and measured almost entirely on people who wrote for fifteen minutes a day for four days.
The largest meta-analysis of experimental writing studies (146 randomized studies) found a small but statistically significant benefit, r = .075. The most-quoted figure, d = .47, comes from a much earlier and much smaller review of 13 studies. A 2022 meta-analysis of 20 randomized trials in mental-health settings found about 5 percentage points more improvement than controls, larger for anxiety and PTSD than for depression. Nearly all of this evidence tests a short, structured writing exercise, not the ordinary practice of keeping a journal.
The numbers
The average effect of experimental disclosure, pooled across 146 randomized studies. Positive and statistically significant, and small: this is the best single estimate available, because it is the one with the most studies behind it.
Roughly equivalent to d = 0.15. For scale, a small effect by Cohen's conventions is d = 0.2.
Frattaroli, J. (2006). Experimental disclosure and its moderators: a meta-analysis. Psychological Bulletin, 132(6), 823-865.The overall effect of written emotional expression across 13 studies of healthy participants, sometimes reported as a 23 percent improvement in overall health. Health improved on four outcome types: reported physical health, psychological well-being, physiological functioning, and general functioning. Health behaviours did not change.
This is the number almost every journaling article is quoting, usually without the sample. Thirteen early studies is a thin base, and the later 146-study review found an effect about a third the size.
Smyth, J. M. (1998). Written emotional expression: effect sizes, outcome types, and moderating variables. Journal of Consulting and Clinical Psychology, 66(1), 174-184.How much more the journaling groups improved on standardized symptom scales than controls, across 20 randomized controlled trials of journaling in the management of mental illness. The overall effect sat between d = 0.2 and d = 0.5: a real but modest clinical benefit.
Broken down: anxiety improved 9 percent against 2 percent in controls, PTSD 6 percent against 0 percent, and depression 4 percent against 2 percent. Neither the style of journaling nor the target disorder significantly explained the differences between studies.
Sohal, M., Singh, P., Dhillon, B. S., & Gill, H. S. (2022). Efficacy of journaling in the management of mental illness: a systematic review and meta-analysis. Family Medicine and Community Health, 10(1), e001154.The protocol the whole field is built on. Students wrote for fifteen minutes on four consecutive days, either about a traumatic experience or about a trivial topic. Those who wrote about the difficult thing made fewer visits to the health centre over the following six months.
Worth sitting with: the founding study of expressive writing measured an hour of writing in total, and the outcome was a count of doctor visits.
Pennebaker, J. W., & Beall, S. K. (1986). Confronting a traumatic event: toward an understanding of inhibition and disease. Journal of Abnormal Psychology, 95(3), 274-281.The most robust result across the three gratitude-journal experiments that most gratitude writing ultimately cites. The gratitude-listing groups showed heightened well-being on several, though not all, outcome measures, relative to groups listing hassles or neutral events.
The single tidy percentages often attached to this work are tidier than the paper. What it supports is a consistent lift in positive affect, not a fixed percentage gain in happiness.
Emmons, R. A., & McCullough, M. E. (2003). Counting blessings versus burdens: an experimental investigation of gratitude and subjective well-being in daily life. Journal of Personality and Social Psychology, 84(2), 377-389.How to read an effect size
Most journaling statistics are effect sizes wearing a percentage costume. Two conventions cover almost everything on this page. Cohen's d is the difference between two groups measured in standard deviations. The correlation r is the strength of an association, on a scale from -1 to 1, where 0 is no association at all.
- d = 0.2A small effect. Real, and usually invisible to the person having it.
- d = 0.5A medium effect. Noticeable if you were looking for it.
- d = 0.8A large effect. No pooled estimate in the journaling literature is here.
- r = .075About d = 0.15. The best-supported estimate for expressive writing.
- r = .10Conventionally a small correlation.
So: an intervention that costs an hour, needs no equipment, has no side-effect profile worth speaking of and produces a small positive average effect. That is a genuinely good trade. It is not the thing that fixes your life, and articles that present it that way are the reason this page exists.
What the numbers do not say
They do not measure keeping a journal
Nearly every study here tests a short structured exercise: write about a difficult experience, for fifteen or twenty minutes, on three or four consecutive days, in a lab or as homework. That is not what most people mean by journaling. If you keep a notebook for a decade, nobody has measured what you are doing, and it is a mistake to claim the expressive-writing numbers for it in either direction.
They do not promise it feels good
Writing about a painful experience commonly makes people feel worse immediately afterwards, and the research says so plainly. The measured benefits show up later, on the horizon of weeks and months. A page that leaves you unsettled for an evening is a normal outcome of the exercise, not a sign of doing it wrong.
They are not a treatment
The 2022 review is explicit that journaling is an adjunct with a modest effect, not a substitute for care. If you are in a hard season, a journal is a good thing to have and a poor thing to rely on alone.
They carry the usual caveats
Small samples, undergraduate participants, short follow-ups, and the publication bias that affects every literature of this kind. The gap between the 13-study estimate and the 146-study estimate is exactly the shape you would expect when early promising results are followed by larger and cooler ones.
Sources, and citing this page
Every number above is traceable. If you are writing about journaling, please cite the original studies rather than this page; if the summary itself is useful, link to it.
- Pennebaker, J. W., & Beall, S. K. (1986). Confronting a traumatic event: toward an understanding of inhibition and disease. Journal of Abnormal Psychology, 95(3), 274-281.
- Smyth, J. M. (1998). Written emotional expression: effect sizes, outcome types, and moderating variables. Journal of Consulting and Clinical Psychology, 66(1), 174-184.
- Emmons, R. A., & McCullough, M. E. (2003). Counting blessings versus burdens: an experimental investigation of gratitude and subjective well-being in daily life. Journal of Personality and Social Psychology, 84(2), 377-389.
- Baikie, K. A., & Wilhelm, K. (2005). Emotional and physical health benefits of expressive writing. Advances in Psychiatric Treatment, 11(5), 338-346. The clearest short overview if you are starting from nothing.
- Frattaroli, J. (2006). Experimental disclosure and its moderators: a meta-analysis. Psychological Bulletin, 132(6), 823-865.
- Sohal, M., Singh, P., Dhillon, B. S., & Gill, H. S. (2022). Efficacy of journaling in the management of mental illness: a systematic review and meta-analysis. Family Medicine and Community Health, 10(1), e001154.
Questions
Does journaling actually work?
On average, yes, and by less than most articles claim. The largest meta-analysis of experimental writing studies (Frattaroli, 2006, 146 randomized studies) found a positive and statistically significant average effect of r = .075, which is a small effect. A 2022 meta-analysis of 20 randomized trials of journaling in mental-health treatment found a modest clinical benefit, roughly 5 percentage points more improvement on symptom scales than controls, with larger changes for anxiety and PTSD than for depression.
Where does the "journaling improves health by 23 percent" statistic come from?
From Smyth's 1998 meta-analysis in the Journal of Consulting and Clinical Psychology, which pooled 13 studies of written emotional expression in healthy participants and reported an overall effect of d = .47, sometimes translated as a 23 percent improvement. It is a real finding from a small set of early studies. The much larger 2006 meta-analysis of 146 studies found an effect roughly a third that size, which is the number to quote if you are quoting one.
How long do you have to journal for it to help?
The classic expressive-writing protocol is 15 to 20 minutes a day for three or four consecutive days, and that is what almost all of the evidence tests. Nothing in the literature establishes that a longer or lifelong practice produces proportionally larger effects, because almost nobody has studied one. If you keep a journal for years, you are doing something the research has not measured.
Is journaling effective for anxiety and depression?
The 2022 meta-analysis reported larger descriptive improvements for anxiety (9 percent versus 2 percent in controls) and PTSD (6 percent versus 0 percent) than for depression (4 percent versus 2 percent), with an overall effect between d = 0.2 and d = 0.5. That is a modest adjunct, not a treatment. It is not a substitute for care, and expressive writing about trauma can be distressing in the short term.
Does gratitude journaling work?
Emmons and McCullough's 2003 studies, the ones most gratitude articles are ultimately citing, found heightened well-being in the gratitude-listing groups on several but not all outcome measures across three experiments, with the effect on positive affect the most robust. The often-repeated single percentage figures attached to that work are usually tighter than the paper itself is. There are gratitude journal prompts here if you want to try it rather than read about it.