Study does not find ‘short breaks induce mental exhaustion’

Several publications have misreported the findings of a study that looks at the effects of working for seven hours with short breaks on cognitive function. The reports incorrectly stated that “taking short breaks induced mental exhaustion”, which was not what the study found.

The study’s lead author told Full Fact that this statement does not accurately present its findings. 

The study found that engaging in seven hours of mental work—even with short breaks—can negatively impact cognitive efficiency, suppress brain neural network activity and cause mental fatigue. Participants had not fully recovered from these effects after resting for four and a half hours.

The study did not find that short breaks “induced” mental exhaustion but instead that short breaks were not enough to prevent cognitive performance from declining after working for several consecutive hours.

A report on the study was written by PA Media and appeared in several publications, including in the Daily Mail both in print and online on 5 April and the Independent on 14 April.

It appears that the error originally came from an email newsletter sent to specialist journalists by the academic publishing company, Elsevier. This newsletter, which is not available to the public, incorrectly summarised the findings of the report by saying short breaks were found to induce fatigue. The copy had been approved by Professor Brazaitis before it was sent.

Subsequently, PA Media reported that the study found that “regular short breaks induced mental exhaustion”, which “in turn affected participants’ ability to focus and had an impact on cognitive functions such as attention, learning and visual recognition”.

These claims were repeated in the articles published by the other outlets, which all used the exact phrase “short breaks induced mental exhaustion”.

But this does not represent what the study actually showed.

The Daily Mail used the headline: “Don’t tell the boss! Breaks are bad for your work”. The online version carried a similar headline, although it added “Breaks are bad for your work as study finds they don't improve focus or prevent fatigue”. 

After receiving a request from Full Fact, the error has been corrected by PA Media, the Independent and in the Daily Mail’s online article.

What did the study show?

The study, which was published in the International Journal of Psychophysiology, did not look at the “effectiveness of 10-minute breaks on work performance”, as the Daily Mail says, but rather the cognitive effects of working for a seven hour period including short breaks.

Researchers from the Lithuanian Sports University analysed the effect of a seven hour day of “office-like work”—with 10-minute breaks every 50 minutes—on cognitive function, motivation, mood and central nervous system activity. 

The study took blood tests and brain scans from a sample of 18 men aged between 23 to 29 years old. These results were compared to the same measurements on a day where the participants did not do similar work at all. 

Without the results being compared to readings from participants who worked for the same period but without breaks, it is not possible to conclude whether the breaks themselves cause mental exhaustion—rather than simply the effect of working for long hours. 

What the study does conclude is that the 10-minute breaks do not prevent someone from becoming mentally exhausted by seven hours of work, and that there was no increase in cognitive efficiency in the 50 minutes of work after taking a short break. 

The study’s lead author, Professor Marius Brazaitis, told Full Fact that “the short breaks during the working day are NOT the cause of mental fatigue.”

“Moreover, in our study design, we did not isolate the short breaks, mainly because it’s impossible to make the participants work for 7 hours without any breaks, for instant, using the WC [sic].”

The PA Media article also said that the researchers thought the reason short breaks cause  mental exhaustion could be “because dipping in and out of a task can overstimulate the brain, leading to fatigue afterward.”

However, Professor Brazaitis said that “there is no such indication” for this theory in the paper.

The study’s abstract reads: “Our study found that engaging in 7 h of mental work similar to that found in an office environment, with 10-min breaks every 50 min, can negatively impact cognitive efficiency, suppress brain neural network activity, and cause mental fatigue. These effects do not fully recover after a 4.5-h rest.”

Both in the abstract and the study itself, it emphasises that the study is looking at whether the short breaks can “prevent” cognitive function from declining, rather than whether they cause this. 

The abstract says that “taking short breaks during the workday does not prevent mental exhaustion or impairment in cognitive function”, but does not suggest these breaks cause this exhaustion. The study also refers to other research that demonstrates the benefits of taking work breaks on individual well-being and performance.

Full Fact has previously written about other instances where scientific research has been misreported in the media, such as a study about prostate cancer and another on childhood infections. 

Image courtesy of Posse Senadores