Does Pennebaker's Expressive Writing Exercise Work? The 4-Day Instructions and the Effect Sizes
Pennebaker's expressive writing exercise is 15-20 minutes a day for 4 days. The original instructions, plus what Smyth, Frattaroli and Guo found: small effects.
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In the 1988 study that made expressive writing famous, fifty undergraduates were sent to individual private rooms and given 20 minutes a day, for four days, to write. Half of them described neutral things such as the shoes they were wearing and their plans for the rest of the day. The other half wrote about the most upsetting experiences of their lives.
That is the whole exercise. Expressive writing is a structured way to get one unresolved mess out of your head and onto paper, and it is the most-studied way to do so. It differs from a to-do dump because the target is thoughts and feelings about one issue, and from a morning journaling habit because it runs for four days and then stops. The effect is small, and the numbers are below.
What are the exact steps of the four-day exercise?
- Book four consecutive days. Put four sessions of 20 minutes in the calendar before you start. If the first one needs an early start, DontSnooze can attach a consequence to the wake-up so day 3 does not quietly slip.
- Pick a private place. Pen or keyboard is your call. The original sessions took place in individual private rooms, and Frattaroli found larger effects in studies where disclosure was private.
- Choose one issue. The 1988 instructions (Pennebaker, Kiecolt-Glaser and Glaser, Journal of Consulting and Clinical Psychology) said to write about the most traumatic and upsetting experiences of your life, on a different topic each day or the same one throughout. For a pile-up, pick the item under the pile, the one you avoid.
- Start the timer: 20 minutes. The 1988 sessions were 20 minutes; a later trial (Rude et al., 2023) used 15. Frattaroli’s meta-analysis found sessions of at least 15 minutes beat shorter ones.
- Write your deepest thoughts and feelings. That wording comes from the 1988 instructions. Cover what happened and how you feel about it. If “bad” is the only word you have, sorting it into finer emotion words helps. Skip the task list.
- Ignore form. Frattaroli describes instructions telling writers to “let go” and not to worry about spelling, punctuation or grammar. When you run dry, keep the pen moving by repeating the last thought.
- Close the session, then move. After writing, walk or do something physical for ten minutes. The 1988 writers reported more physical symptoms and more negative mood right afterward.
- Repeat on days 2 to 4, then stop. If you miss a day, write the next day and finish the four rather than restarting from day 1. Judge the effect weeks later.
Do the sessions earlier in the day if writing winds you up; if the issue is mostly a midnight mental loop, that is a different problem with its own fixes.
What did the original studies find?
Pennebaker and Beall (1986, Journal of Abnormal Psychology) assigned college students to write about upsetting experiences, only the facts, only the emotions, or a neutral topic. According to Frattaroli’s account, only the group that wrote about facts and emotions together had fewer illness-related doctor visits several weeks later.
The 1988 study found something similar: the trauma writers made fewer student-health-center visits for illness than the control group (F(1,48) = 4.20, p < .05), and they felt worse immediately after each session (negative mood, p < .001).
How big is the effect across all the studies?
| Review | Sample | Result |
|---|---|---|
| Smyth (1998), J Consulting and Clinical Psychology | Written emotional expression studies | Better reported physical health, psychological well-being, physiological functioning and general functioning; no change in health behaviors; distress rose right after writing |
| Frattaroli (2006), Psychological Bulletin | 146 randomized studies | Average r = .075 (Cohen’s d = .151) |
| Guo (2023), British Journal of Clinical Psychology | 31 randomized trials, N = 4,012, healthy and subclinical samples | Hedges’ g = -0.12 (95% CI -0.21 to -0.04) for depression, anxiety and stress symptoms |
An r of .075 accounts for 0.56 percent of the variance in outcomes, which Frattaroli concedes is small by Cohen’s conventions. Her translation: in a hypothetical 100-versus-100 trial, 54 percent of writers improve against 46 percent of controls. She compares it with daily aspirin after a heart attack (r = .034) and argues that, because writing costs almost nothing, any positive effect is worth having. Earlier fixed-effects reviews had found larger averages (.257 for Smyth, .084 for Frisina et al., 2004); Frattaroli attributes the gap partly to her including 48 percent unpublished studies versus 23 percent in Smyth’s.
Newer trials are mixed. In Rude and colleagues (2023, Frontiers in Psychology), 15-minute sessions on three closely spaced days under standard instructions did not significantly beat a control task on self-reported depression two weeks later. Versions that added encouragement to accept emotions did, among people who wrote longer essays.
Which conditions went with bigger effects?
| Condition | Smaller effect (r) | Larger effect (r) |
|---|---|---|
| Number of sessions | Fewer than 3: .040 | 3 or more: .082 |
| Session length | Under 15 minutes: -.007 | 15 minutes or more: .080 |
Frattaroli also found larger effects in samples with physical health problems or a history of trauma or stressors, and when people wrote about more recent events.
When should you not do this alone?
- It can hurt first. Both the 1988 study and Smyth’s review found distress rising right after writing. Stop and do something calming if it spikes.
- It is not therapy. The earliest work used mostly healthy college students, and an average r of .075 is a nudge. If low mood, panic or sleep trouble lasts weeks, see a clinician; if the memory involves abuse or violence, work through it with a professional.
- Crisis is a different job. If you have thoughts of harming yourself, contact your local emergency number or a crisis line (988 in the US) rather than a notebook.
Frattaroli tried to cluster the 22 moderators she found into a handful of factors, and they did not group in any interpretable way, so which ingredients matter most remains open.
Frequently asked questions
Does the topic have to be a trauma or a secret?
No. The 1988 instructions asked for the most upsetting experiences of a person’s life, ideally ones not yet discussed in detail, but other trials had incoming students write about coming to college (Pennebaker and Francis, 1996). Frattaroli (2006) found topic valence did not significantly change effect sizes, though instructing people to write on previously undisclosed topics was linked to larger ones.
Is handwriting better than typing?
Frattaroli’s 2006 meta-analysis found the mode of disclosure (handwriting, typing or talking) did not significantly moderate effect sizes. Use whichever lets you keep going for the full timer. Privacy mattered more: studies where participants disclosed in a private setting, and at home, tended to show larger effects.
How soon will I feel any different?
Do not expect it by day 4. In Frattaroli’s data, studies that followed participants for under a month had a larger average effect (r = .111) than those following them for a month or more (r = .064). Guo’s 2023 review of trials with long follow-ups reported that the benefit on depression, anxiety and stress symptoms emerged after a delay.
Why do researchers say to write on consecutive days?
Guo (2023) split trials by the gap between sessions and found that gaps of 1 to 3 days produced a stronger effect than gaps of 4 to 7 days or longer. Frattaroli found the spacing of sessions was not a significant moderator, so the evidence for compressing them is real but not settled.