Friday March 13 2015
Does feeling low slow down time?
"How depression affects our sense of time: Hours drag on and even stand still," is the somewhat over-hyped headline from the Mail Online.
As the old saying goes – Time flies when you’re having fun. So does the reverse also ring true? Does feeling depressed slow down your perception of time? Two German researchers tried to find out.
They pooled the results of previous studies, which lead to 433 depressed people being compared with 485 non-depressed people. The results tentatively suggest that some people with depression may perceive time as going more slowly than those without.
No difference was found in their ability to estimate actual time durations in tests (for example, trying to judge when a minute had passed).
The study has a number of limitations, meaning we should be cautious in assuming that the findings are reliable. Their statistical methods, for example, made it more likely to find a statistically significant result by chance and they noted that using other methods would have wiped out any differences between the groups.
The clinical implications of this potential time perception difference are also unclear. Can knowing that people with depression perceive time as progressing slowly help their care or support?
The study provides little in the way of answers, but may stimulate useful debate.
Where did the story come from?
The study was carried out by researchers from Johannes Gutenberg-Universität Mainz, Germany, who report receiving no external funding for the work.
The study was published in the peer-reviewed Journal of Affective Disorders.
The Mail Online reported the story at face value and did not discuss any of its limitations. Its choice of headline, "Hours drag on and even stand still", is an exaggeration of the findings.
It included interviews with the study authors, who said their results confirmed anecdotal reports from hospital and private practice staff that: "depressed patients feel that their time only creeps forward slowly or is passing in slow motion". Anecdotal reports, while interesting, are not evidence.
What kind of research was this?
This was a meta-analysis pooling the results of studies looking at time perception of people with depression.
The study authors say that "depressive patients frequently report to perceive time as going by very slowly", but previous studies on the topic have given inconsistent results. They wanted to pool the past results to see if there was any overall effect. This pooling of many independent studies is called a meta-analysis.
A meta-analysis is an appropriate and potentially powerful way of studying the issue. However, the meta-analysis is only as good as the studies feeding it.
What did the research involve?
The team pooled the results from 16 individual studies in which 433 depressed people (cases) and 485 non-depressed people (controls) participated. The main analysis looked for differences in measures of time perception between the two groups.
To identify as much relevant material as possible, the researchers searched for published evidence online (using a Web of Science search) and called for unpublished information to be submitted by more than 100 experts in the field.
Studies were only included if they were in adults, had a control group of non-depressed people, had diagnosed depression using standardised criteria, and had sufficient statistical information to enable the pooling of estimates.
In the included studies, the participants were asked to estimate the duration of periods of time.
For example, they were asked to estimate the length of a film in minutes, press a button for five seconds, or discriminate the duration of two sounds. Studies measured time durations ranging from the ultra-short (less than a second) to the long (greater than 10 minutes).
They were also asked about their perception of whether time flowed quickly or slowly. This typically used visual scales, requiring the participant to mark a point on a line ranging from very fast to very slow.
What were the basic results?
The main results showed that people with depression were no different than people without at judging time duration.
However, the subjective perception of how time flowed did differ between the groups. People with depression perceived time as going more slowly than those without.
In effect, this meant that both groups could estimate time to the same accuracy, but the people with depression perceived the time to be passing much more slowly.
How did the researchers interpret the results?
The team concluded: "Depression has medium effects on the subjective flow of time, whereas duration judgments basically remain unaffected."
Having compared 433 depressed people with 485 non-depressed people, the study suggests that some people with depression perceive time as going more slowly than those without. No difference was found in their ability to actually estimate duration of time on testing, but people with depression rated time generally as flowing more slowly.
People with low mood often have associated feelings of little enjoyment in daily life and normal activities, and feelings of being hopeless or helpless. As such, the idea that they may perceive time as passing by more slowly seems plausible, and point to a possible phenomenon to be investigated further. However, the findings do not prove this outright. The study authors themselves advised caution when interpreting the findings. For example, the results weren’t able to take account of any influence of the use of medications or treatments for depression, such as psychotherapy. These could potentially influence time perception.
More importantly, their use of statistical methods made it more likely to find a statistically significant result by chance. They note that by using other methods, none of their findings would have reached statistical significance.
The clinical implications of this time perception are also unclear. Can knowing that people with depression perceive time as progressing slowly help their care or support?
As a result, it would be beneficial to see more robust research in this area before believing this is a widespread occurrence, and a clearer rationale for its importance.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.