Lethargy is a state of tiredness, weariness, fatigue, or lack of energy. It can be accompanied by depression, decreased motivation, or apathy. Lethargy can be a normal response to boredom, inadequate sleep, overexertion, overworking, stress, lack of exercise, or a symptom of a disorder. When part of a normal response, lethargy often resolves with rest, adequate sleep, decreased stress, and good nutrition.[21][22]
There are three types of boredom, all of which involve problems of engagement of attention. These include times when we are prevented from engaging in wanted activity, when we are forced to engage in unwanted activity, or when we are simply unable for some other reason to maintain engagement in an activity.[13] Boredom proneness is a tendency to experience boredom of all types. This is typically assessed by the Boredom Proneness Scale.[14] Recent research has found that boredom proneness is clearly and consistently associated with failures of attention.[15] Boredom and its proneness are both theoretically and empirically linked to depression and similar symptoms.[16][17][18] Nonetheless, boredom proneness has been found to be as strongly correlated with attentional lapses as with depression.[16] Although boredom is often viewed as a trivial and mild irritant, proneness to boredom has been linked to a very diverse range of possible psychological, physical, educational, and social problems.[19]
Only in the last decade has there been much scientific research looking into the nature of boredom. In 2006, a study classified boredom into four different types, with a follow-up study published this month in the journal Motivation and Emotion adding a fifth kind of boredom, called apathetic boredom, to the list. The researchers involved in the study had 63 university students and 80 high school students answer smartphone-based surveys about their activities and experiences over the course of two weeks.

Erich Fromm and other thinkers of critical theory speak of boredom as a common psychological response to industrial society, where people are required to engage in alienated labor. According to Fromm, boredom is "perhaps the most important source of aggression and destructiveness today." For Fromm, the search for thrills and novelty that characterizes consumer culture are not solutions to boredom, but mere distractions from boredom which, he argues, continues unconsciously.[29] Above and beyond taste and character, the universal case of boredom consists in any instance of waiting, as Heidegger noted, such as in line, for someone else to arrive or finish a task, or while one is travelling somewhere. The automobile requires fast reflexes, making its operator busy and hence, perhaps for other reasons as well, making the ride more tedious despite being over sooner.
The bored antihero became prominent in early 20th century existentialist works such as Franz Kafka's The Metamorphosis (1915),[43] Jean-Paul Sartre's La Nausée (1938) (French for 'Nausea'),[44] and Albert Camus' L'Étranger (1942) (French for 'The Stranger').[45] The protagonist in these works is an indecisive central character who drifts through his life and is marked by ennui, angst, and alienation.[46]
Boredom is a condition characterized by perception of one's environment as dull, tedious, and lacking in stimulation. This can result from leisure and a lack of aesthetic interests. Labor and art may be alienated and passive, or immersed in tedium. There is an inherent anxiety in boredom; people will expend considerable effort to prevent or remedy it, yet in many circumstances, it is accepted as suffering to be endured. Common passive ways to escape boredom are to sleep or to think creative thoughts (daydream). Typical active solutions consist in an intentional activity of some sort, often something new, as familiarity and repetition lead to the tedious.

In a learning environment, a common cause of boredom is lack of understanding; for instance, if one is not following or connecting to the material in a class or lecture, it will usually seem boring. However, the opposite can also be true; something that is too easily understood, simple or transparent, can also be boring. Boredom is often inversely related to learning, and in school it may be a sign that a student is not challenged enough, or too challenged. An activity that is predictable to the students is likely to bore them.[31]
In contexts where one is confined, spatially or otherwise, boredom may be met with various religious activities, not because religion would want to associate itself with tedium, but rather, partly because boredom may be taken as the essential human condition, to which God, wisdom, or morality are the ultimate answers. Many existentialist philosophers, like Arthur Schopenhauer, espouse this view. This view of religiosity among boredom does affect how often people are bored. People who had a higher religiosity while performing boring task, reported less boredom than people of less religiosity. People performing the meaningless task had to search less for meaning.[24]
A 1989 study indicated that an individual's impression of boredom may be influenced by the individual's degree of attention, as a higher acoustic level of distraction from the environment correlated with higher reportings of boredom.[32] Boredom has been studied as being related to drug abuse among teens.[33] Boredom has been proposed as a cause of pathological gambling behavior. A study found results consistent with the hypothesis that pathological gamblers seek stimulation to avoid states of boredom and depression.[34] It has been suggested that boredom has an evolutionary basis that encourages humans to seek out new challenges. It may influence human learning and ingenuity.[35]
“Boredom – the psychological state that we experience whenever we are uninterested in what we are currently doing – is one of the defining traits of humanity. Time is the psychological nemesis of humankind. Tedium, a fundamental angst of humankind, arises from human beings’ ability to perceive time and our attempts to derive meaning from our personal existence.”
A "banishment room" (also known as a "chasing-out-room" and a "boredom room") is a modern employee exit management strategy whereby employees are transferred to a department where they are assigned meaningless work until they become disheartened enough to quit.[37][38][39] Since the resignation is voluntary, the employee would not be eligible for certain benefits. The legality and ethics of the practice is questionable and may be construed as constructive dismissal by the courts in some regions.
Although it has not been widely studied, research on boredom suggests that boredom is a major factor impacting diverse areas of a person's life. People ranked low on a boredom-proneness scale were found to have better performance in a wide variety of aspects of their lives, including career, education, and autonomy.[30] Boredom can be a symptom of clinical depression. Boredom can be a form of learned helplessness, a phenomenon closely related to depression. Some philosophies of parenting propose that if children are raised in an environment devoid of stimuli, and are not allowed or encouraged to interact with their environment, they will fail to develop the mental capacities to do so.
Some individuals are more likely to be bored than others. People with a strong need for novelty, excitement, and variety are at risk of boredom. These sensation seekers (e.g., skydivers) are likely to find that the world moves too slowly. The need for external stimulation may explain why extroverts tend to be particularly prone to boredom. Novelty seeking and risk-taking is the way that these people self-medicate to cure their boredom.