In The Hitchhiker's Guide to the Galaxy, by Douglas Adams, a desultory robot named Marvin struggles to get through his days. Possessed of “a brain the size of a planet,” he is 50,000 times more intelligent than a human, yet he cannot solve his own biggest problem: an unshakable ennui.

“The first ten million years were the worst,” Marvin recounted at one point. “And the second ten million years, they were the worst too. The third ten million years I didn't enjoy at all. After that I went into a bit of a decline.”

We all have suffered episodes of tedium, if not on the same scale: a dinner date that drags on, a meeting conducted in monotone, an interminable wait for a bus. As the minutes tick by, a slight anxiety may pervade your thoughts. You drum your fingers quietly on your knee. You bounce in your seat. But nothing—not playing the guitar nor heading to the gym nor reading a new detective novel—seems up to the task of shaking boredom's death grip on your mind.

The nature of boredom has long puzzled thinkers in literature, philosophy and psychology. German philosopher Martin Heidegger described it as “drifting hither and thither in the abysses of existence like a mute fog.” Others have likened it to nausea. Recent research suggests that chronic boredom is often, but not always, accompanied by depression. It also seems to manifest in one of two forms, which my colleagues and I refer to as apathetic and agitated boredom. By studying groups of people who tend to suffer this condition more acutely—including individuals who have sustained traumatic brain injuries—we are beginning to identify the cognitive processes and brain regions that may support the experience. Although boredom is commonplace, we are now learning that excessive amounts of it can harm our health. Before we can address these concerns, though, we need to look more closely at the phenomenon itself.

The Milquetoast Mind

Humans have likely weathered stretches of tedium for as long as our forebears have had free time. The growth of leisure time, often seen as a product of the industrial revolution, heightened the odds of a mind coming up empty when tasked with entertaining itself. In Charles Dickens's novel Bleak House, set during this time of societal transition, Sir Dedlock tenderly asks his wife, “Is it still raining, my love?” To which she replies: “Yes, my love. And I am bored to death with it. Bored to death with this place. Bored to death with my life. Bored to death with myself.” Through Lady Dedlock's plight, Dickens introduced a new English word into the written canon—boredom.

In 1885 Sir Francis Galton casually measured boredom in a meeting, which he reported in an article in Nature entitled “The Measure of Fidget.” He claimed that when the audience was transfixed by the speaker “each person forgets his muscular weariness and skin discomfort, and he holds himself rigidly in the best position for seeing and hearing.” When the spell was broken, “several individuals cease to forget themselves and they begin to pay much attention to the discomforts attendant on sitting long in the same position.” He even tracked the amplitude and period of swaying heads and trunks as the audience's attention fluctuated.

Today when measuring boredom, we tend to use a variety of questionnaires, the first of which was published in 1986 by Richard Farmer and Norman Sundberg, then both at the University of Oregon. Using their boredom proneness scale and other tests, psychologists have found that boredom is linked with worse performance at work and school, lower job satisfaction, more frequent lapses in attention, and heightened rates of drug and alcohol abuse. It also appears to have detrimental effects on the treatment and rehabilitation of mental disorders.

Despite a growing body of research showing the negative effects of boredom, we still lack one critical thing: a clear-cut definition. Part of the challenge is that boredom for one person may only loosely resemble another's ennui. The placid but unmotivated couch potato looks nothing like the agitated child pleading for something interesting to do. The nature of any one person's episodes of boredom may also vary.

Resolving some of these ambiguities has been the focus of recent work in my laboratory at the University of Waterloo. In a study published in 2011 my graduate student Yael K. Goldberg and our collaborators asked 823 students to fill out questionnaires that assessed several aspects of boredom, such as how prone they are to it and how well they cope with it. We also administered widely used questionnaires for measuring apathy, anhedonia and depression. To make sense of all their answers—and to see how boredom might differ from those other states—Goldberg used structural equation modeling, a statistical technique that examines the relations between concepts.

We found that the more bored a volunteer was, the more likely he or she was to express both depressive symptoms and low motivation. Yet boredom did not always co-occur with a lack of motivation, nor was it always a sign of depression. Despite these overlaps, it seemed to occupy its own psychological space. Earlier work supports this idea. In a 2003 study psychiatrist Dale Theobald, now at Community Home Health near Indianapolis, and his colleagues administered citalopram, a common antidepressant, to cancer patients who were suffering from depression. They found that the symptoms of boredom and depression abated at different rates, suggesting that the two conditions involve distinct mechanisms.

Unpublished data from our 2011 study indicates one component of boredom that may drive the correlation with depression. The boredom proneness scale can be divided into two subscales that measure a person's capacity for being satisfied by internal versus external sources of stimulation. An internally stimulated person, for example, would tend to agree with statements such as “In any situation I can usually find something interesting to do,” and “I often wake up with a new idea.

An externally stimulated person is more likely to find resonance with sentiments such as “I am often trapped in situations where I do meaningless things,” and “It takes a lot of change and variety to keep me very happy.” Most people fall between these two extremes—often able to amuse ourselves but from time to time itching for something new from the outside world. Our data suggest that people who rely heavily on external stimulation and fail to secure sufficient amounts of it are more likely to also report symptoms of depression.

In work published in 2012 and led by one of my students, Ela Malkovsky, we have found that the division between internal and external stimulation can help us define two distinct subtypes of boredom. In this study we had people complete questionnaires exploring boredom proneness, lapses in attention and adult symptoms of attention-deficit hyperactivity disorder (ADHD).

We could cluster our subjects into two groups based on their propensity to experience boredom and more specifically on their need for either internal or external stimulation. People of the first subtype, which we might colloquially label the couch potato, do not report gaining much satisfaction from internal sources of stimulation and show no motivation to seek gratification externally. We labeled this condition apathetic boredom. Suboptimal as their state may be, these individuals tend not to fret about it.

The second subtype involves considerably more distress. People in this category rely heavily on external stimulation, and when life falls short they experience intense inner turmoil—we termed their condition agitated boredom. It coincided more with symptoms of ADHD, in particular signs of hyperactivity, than did apathetic boredom. Observations such as Galton's suggest that people afflicted with agitated boredom feel a physical discomfort, a drive to expend energy through motor actions to shake off the boring experience. The jittery knees bobbing up and down and the restless fingers drumming on the desk both signal that agitated boredom is afoot. Whereas the apathetically bored individual does little to change his or her state, the agitatedly bored person is highly motivated to escape this plight. These people would likely agree with a quip attributed to theologian Paul Tillich: “Boredom is rage spread thin.”

Some psychologists, including my Waterloo colleagues Daniel Smilek and J. Allan Cheyne, have suggested that the answer may lie in failures of one's ability to control attention. The idea is that lapses in focus, such as pouring orange juice on your cereal, reflect disengagement from one's surroundings. Boredom could turn out to be the product of a disconnection between our thoughts and the external environment. We may go to a jazz club expecting a fun-filled night of music, yet an inability to focus our attention on it drains all color from the evening. This lack of immersion in the world outside our head could lead us to evaluate our experiences as meaningless. Research on people with traumatic brain injuries, who are at a greater risk of experiencing boredom, is hinting that this might be the case.

Tedium and Trauma

You might wonder what could prompt an academic psychologist to study, of all things, boredom. Just like most parents, I have no trouble summarily dismissing my children when they claim they are bored, and I, too, end up telling them to go find something to do. If only it were so easy.

I started down this path after my brother got into a car crash. To say he was badly injured is a supreme understatement. After a prolonged medication-induced coma and months of recovery—much of which he cannot recall—he began piecing his life back together.

His one true love has always been music. A wrist injury made it physically challenging to get back to drumming, but it was boredom that compounded the challenge. He told me one day, with intense frustration in his voice, that after the crash he was always bored. The challenge to find anything that was stimulating would become a defining feature of life for him.

Some years later, while working with an organization that helped people who had sustained traumatic brain injuries (TBIs), I happened to ask some of the clients if they were more often bored after their injuries. Many of them practically leaped out of their chairs at the question. It turned out boredom was one of the most salient aspects of their present lives, yet no one had ever asked them about it before.

So I set out to explore the relation between boredom and depression in people who have suffered brain traumas. The most common causes of TBIs are incidents involving rapid acceleration and deceleration, such as car accidents or, with less severity, concussions. An injury that shakes the brain around inside the skull can lead to widespread brain damage.

In one experiment with my research group, we asked 14 TBI patients, as well as 33 people who had suffered concussions and 88 healthy individuals, to complete questionnaires that measured their depression and boredom. We found that the people who suffered the most from both maladies also reported the greatest need for external stimulation. This relation was statistically strongest in the TBI group.

People who have suffered an intense blow to the head often demonstrate impulsive, risk-taking behavior postinjury. For example, data suggest that they are more likely to use drugs and alcohol, practice unsafe sex and drive recklessly. We theorized that TBI patients may seek out more extreme activities to find an experience they will evaluate as enjoyable, as if their threshold for satisfaction has been raised.

From a scientific perspective, the optimal experiment to discern whether TBI patients become more reckless after an injury would be to observe healthy people and then evaluate them again after they sustained a TBI. We could never do that, of course, so instead we looked at whether TBI patients generally display more novelty-seeking actions than healthy people.

We had patients perform a simple task, developed by psychologist Elkhonon Goldberg of the New York University School of Medicine and his colleagues, called the cognitive bias task. This admittedly rather boring activity involves showing people geometric shapes that differ in color, shape, size, number or outline. Study participants are repeatedly shown a single shape followed by two different ones. They are asked to rate which of the two subsequent shapes was more like the original and then to decide which figure they prefer. The goal is to see both how well people can recognize the similarities and differences between objects and whether they tend to prefer novel versus familiar objects.

We found that TBI patients had a harder time discriminating between new and familiar things. This result agrees with earlier work on patients with frontal lobe damage, who also struggled more than healthy people when detecting novelty. More important, our study showed that this deficit was greatest in those experiencing agitated boredom. Although the number of patients tested was relatively small, the results were consistent in all three groups—people who were prone to agitated boredom also tended to have a harder time recognizing an object's newness. This hints at an intriguing possibility. Life becomes dull when we cannot distinguish what is fresh and therefore interesting from what is old and familiar—everything gets painted with the same gray brush.

One brain region commonly damaged during acceleration-deceleration injuries is a part of the frontal lobe known as the orbitofrontal cortex (OFC), situated just above the eyes. Scientists have shown that this region is critical for associating events, actions or decisions with their cognitive and emotional evaluations. It helps us mentally code our experiences with a reward value—a process that is essential to how we learn. Your desire to return frequently to your favorite Chinese restaurant involves patterns of neural firing in the OFC, which reflect your evaluations of prior visits and your fondness for the spicy kick of the kung pao chicken. We also make negative associations that might turn out to be erroneous later on—I still avoid creamed corn because of an episode in my youth that ended poorly. Almost certainly some bug or virus led me to feel ill, but my brain labeled creamed corn as the culprit and doomed it to the “do not eat” pile for eternity.

TBI patients, similar to the people with agitated boredom described earlier, may experience a recurring mismatch between their expectations for an event and its actual payoff. This line of inquiry is still young, but therapies may ultimately train patients to better recognize when an event is in fact novel. The goal would be to help them both alter their expectations of rewards and improve their sensitivity to novelty. Although I question the wisdom of viewing boredom as pathology, in some extreme cases it might pose a significant obstacle to a healthy life.

Bored to Death

In a recent British study, epidemiologists Annie Britton and Martin Shipley of University College London examined data collected from civil servants for self-reported boredom and several cardiac risk factors. The civil servants were first assessed in the 1970s on a range of topics, including job satisfaction and boredom. In a follow-up in 2010 they found that those people who reported more ennui were more likely to die younger and to experience cardiac health issues. Literally, people were being bored to death.

The researchers acknowledged the myriad factors that may have contributed to this finding, including poor fitness and unhealthy diet in those reporting high levels of boredom. Boredom may not be the smoking gun, but it is at least a contributing factor or perhaps a warning sign of poorer health outcomes. Another graduate student in my lab, Colleen Merrifield, recently explored physiological responses to boredom by inducing the state in healthy undergraduates. We had people watch either a scene from a tear-jerker movie or a film of two men hanging laundry—a scintillating viewing experience if ever there was one—while measuring their heart rate and levels of cortisol, the hormone most commonly used to assess stress response. We found that the participants who had watched the boring laundry scene had a higher heart rate and higher cortisol levels. Clearly, boredom is not good for your health.

Data on the detrimental effects of boredom hit home for me. Another reason I have devoted myself to this topic is that I have been a poster boy for agitated boredom for most of my life. What the recent research highlights is that the topic is not simple academic curiosity. Boredom appears to represent a key, hitherto unheeded, component of depression, a disorder that afflicts approximately one in 10 of us at any given time. It most likely complicates life for people recovering from brain injuries. Yet it is also a feeling that descends on many of us from time to time, and we have all encountered children tormented by tedium, if not been one of them ourselves. Discovering why we sometimes disengage from life and why once scintillating activities suddenly lose their luster could help us understand the dynamics of everyday living and, perhaps, permit us to bend them to our will.