Someone finally tested the Pomodoro technique

The Pomodoro technique, 25 minutes of work and then a 5-minute break, is in every study-skills book and most timer apps. In 2023 researchers at Maastricht University in the Netherlands published what was, as far as they could find, the first test of the rhythm against an alternative (pp. 353, 355): 87 students, one two-hour session of their own studying, three break schedules, none of them 25 and 5 (pp. 355 to 356). The study could not detect a difference in how much of their list the students said they finished, or in how hard they said they worked. What it found was a difference in how the work felt: the students deciding their own breaks, call them the self-timers, went about 44 minutes at a stretch and arrived at their breaks more tired, more distracted and less willing to go back in (pp. 360 to 361).

Three schedules, one two-hour session

In June 2020, in lockdown, 110 students at a Dutch university opened a study page on their own laptop and worked on their own material for 120 minutes (pp. 356 to 357). At random, some saw a countdown and heard a sound after 24 minutes, then had 6 minutes off, which is the rhythm the paper calls Pomodoro. Some got 12 minutes on and 3 off. The self-timers had a break button and used it whenever they liked (pp. 355, 357 to 358). After drop-out and outliers the analysed sample was 87: 35 self-timers, 25 on 24 and 6, and 27 on 12 and 3 (p. 356; Figure 1, p. 357). Every time a student was about to start a break, the page asked how they felt right then (pp. 357 to 358).

Left alone, the self-timers studied in blocks averaging 44 minutes on the page and rested for about 15, against the 24 and 6 or 12 and 3 the timer imposed (Table 2, p. 360).

What the timer changed

Just before a break, the self-timers felt worse than the two timed groups put together. They reported more fatigue, an effect size¹1 An effect size is a way of saying how big a difference is on a common scale. Here d = 0.5 would mean the two groups differ by half of the spread you see between people in general. ↩ of d = −.46, the minus marking that the self-timers scored higher, which means, roughly, that the average timed student felt less tired than about 68 percent of the self-timers. More distraction, d = −.71, so the average timed student was less distracted than about 76 percent of them. Less concentration, d = .47, the average timed student more concentrated than about 68 percent of them. And less motivation to start again, d = .72, more motivated than about 76 percent (p. 361; Figure 4, p. 361).

What the paper cannot say is why. The self-timers may have been more tired because deciding your own breaks costs something, or simply because they had just worked 44 minutes straight. The authors write that they "cannot be sure" which, "or both" (pp. 363 to 364).

What the study could not tell apart

With 35, 25 and 27 students in the three groups, "no difference" anywhere below means this study could not detect one, not that none exists. How hard they said they worked: the study found no difference between the timed and self-timed students (p. 361). How much of their list they said they finished: on average about 48 percent of roughly three tasks, and no difference between the schedules (p. 362). Satisfaction, enjoyment and a sense of control: none differed significantly (p. 362).

The two timed rhythms barely separated: on effort, concentration and difficulty they did not differ significantly, and on one of seven feelings, interest, the 12-and-3 students scored slightly higher (p. 361).

The abstract says timed breaks "appeared to have efficiency benefits" (p. 353). Total study time in fact did not differ significantly between the groups, falling just short of the usual bar (p = .061)²2 p is roughly how likely a gap this size would be if there were no real difference at all; the usual bar for calling a result significant is .05. ↩, and the Pomodoro group spent the longest time on the page of the three, about 93 minutes against 83 and 74 (Table 1, p. 360). Efficiency is the authors' reading, not a result.

It was not 25 and 5

The paper describes the technique as 25 minutes and 5 (p. 355) and then tests 24 and 6. The paper gives no reason for the change, and the longer fourth break the technique prescribes never came (pp. 355, 358). Nothing here ranks 25 and 5. Nor was there a group with no breaks at all, so the study cannot say breaks beat none.

I didn't let myself get distracted that easily because I was thinking: 'It's only 12 min, I'll do this in the next break.'

What 22 other experiments say

A 2022 meta-analysis³3 A meta-analysis pools many separate studies into one estimate, so the answer rests on a whole literature rather than on whichever study you happened to read. ↩ of 22 controlled studies of breaks of ten minutes or less found, in the nine that measured them, with about 800 people in the fatigue analyses, that a short break raised energy and lowered fatigue by small amounts, d = .36 and .35: the average person after a break reported less fatigue than about 64 percent of the comparison group, who either kept working or took a different break (pp. 2, 8; Table 3, p. 13). On performance the effect was smaller and not significant, d = .16, though a correction for publication bias⁴4 Studies that find something are likelier to be published, so a pooled estimate can be tilted; this correction estimates the tilt. ↩ moved it to a small significant .22 (Table 3, p. 13; p. 16). In those studies, short breaks changed how the work felt; whether they changed the work is open, no study found they hurt it, and none of it speaks to breaks longer than ten minutes (pp. 1, 18).

What it suggests trying

1. Decide the break before you start. The students who chose for themselves went about 44 minutes at a stretch and arrived at the break more tired.
2. Give the break an end time as well as a start. Their breaks ran to about a quarter of an hour, and one wrote that a break "takes way longer than I anticipated" (Appendix 1, p. 366).

A worked example: write any two numbers you can keep on a sticky note, say 24 on and 6 off, the paper's own rhythm, and stop the break when the 6 runs out rather than when you feel like it.

Where Yappie fits

We make Yappie, a focus app with a pet beside the timer, so read this as an interested party. The timer opens at 25 minutes because that is the folk rhythm, not because this study found it. What the study found is that students on a fixed rhythm reported feeling better just before their breaks than students deciding for themselves, and that its two rhythms were hard to tell apart; so the numbers are yours to set, and the break has its own countdown.

References

1. Biwer, F., Wiradhany, W., oude Egbrink, M. G. A., & de Bruin, A. B. H. (2023). Understanding effort regulation: Comparing 'Pomodoro' breaks and self-regulated breaks. British Journal of Educational Psychology, 93(Suppl. 2), 353 to 367. https://doi.org/10.1111/bjep.12593↩
2. Albulescu, P., Macsinga, I., Rusu, A., Sulea, C., Bodnaru, A., & Tulbure, B. T. (2022). "Give me a break!" A systematic review and meta-analysis on the efficacy of micro-breaks for increasing well-being and performance. PLOS ONE, 17(8), e0272460. https://doi.org/10.1371/journal.pone.0272460↩