Fatigue occupies a surprisingly varied terrain in the depth-psychology and allied-sciences corpus. At one pole stands Jung's early experimental work, where fatigue functions as a measurable perturbation of associative attention: states of extreme fatigue produce the same blunted, sound-dominated reaction-types as mania or heavy intoxication, thereby collapsing the boundary between psychopathology and ordinary exhaustion. This finding carries diagnostic weight — a high proportion of sound reactions signals disturbed attention regardless of aetiology. At a second pole, Han's cultural-philosophical analysis transforms fatigue into an existential and social category: the achievement society generates not the immunological fatigue of illness but the 'tiredness of positive potency,' a depletion that strips the ego of its generative openness. Against this Han contrasts what Peter Handke theorises as 'we-tiredness,' a creative, negative potency of not-doing that approaches the sacred. A third register is immunological and interoceptive: Lench and Paulus locate fatigue (as anergia) within cytokine-mediated sickness behaviour, wherein the organism deliberately withdraws motor resources to prioritise immune function. Merleau-Ponty adds a phenomenological corrective: fatigue is never a mere mechanical cause acting on liberty but always bears intrinsic significance for the embodied subject. Across these registers, fatigue indexes the limits of the performance-driven self, marks the threshold between volition and automatism, and functions as both symptom and signal.
in fatigue, i.e., the connections and sound associations were mainly superficial… When we analyze the state of extreme fatigue, it is easy to find similar elements there.
Jung establishes that extreme fatigue produces an associative profile — dominated by superficial sound reactions — structurally identical to manic psychopathology, thereby grounding fatigue as a psychologically diagnostic state.
, Experimental Researches, 1904thesis
The tiredness of exhaustion is the tiredness of positive potency. It makes one incapable of doing something. Tiredness that inspires is tiredness of negative potency, namely of not-to.
Han distinguishes productive, world-opening 'we-tiredness' from the ego-depleting tiredness of the achievement society, revaluing fatigue as a potential site of creative cessation and sacred interval.
, The Burnout Society, 2010thesis
Two feelings contribute to this desirable state: anergia (in the form of fatigue) and anhedonia. Anergia discourages movement itself.
Lench frames fatigue (as anergia) as a functionally adaptive feeling that redirects metabolic resources from voluntary movement to immune defence, implicating pro-inflammatory cytokines as its neurochemical substrate.
, The Function of Emotions: When and Why Emotions Help Us, 2018thesis
pain and fatigue can never be regarded as causes which 'act' upon my liberty, and that, in so far as I may experience either at any given moment, they do not have their origin outside me, but always have a sig
Merleau-Ponty insists that fatigue is not an external mechanical cause impinging on freedom but an internally significant dimension of embodied existence, irreducible to causal explanation.
, Phenomenology of Perception, 1962thesis
a result with 5 per cent internal associations and 27 per cent sound reactions corresponds to a state of heavy intoxication or serious mania or a state of quite abnormal fatigue.
Jung quantifies the diagnostic threshold at which fatigue-induced associative blunting becomes indistinguishable from psychotic states, lending empirical weight to the continuum between normal depletion and pathology.
, Experimental Researches, 1904thesis
Disturbance of attention due to motor excitation in fatigue and alcoholism could in our view be interpreted thus: the physical correlates of the attention phenomenon, the muscular tensions, become under the influence of motor excitation shorter and more variable.
Jung proposes a psychophysical mechanism for fatigue-induced flight of ideas: motor excitation destabilises muscular tension — the substrate of directed attention — producing associative loosening.
, Experimental Researches, 1904supporting
we also tried to supplement our material in other directions… we took associations from some of our subjects in a condition of obvious fatigue. We were able to obtain such reactions from six subjects.
Jung describes the methodological design of fatigue conditions in the association experiment, situating fatigue as a controlled independent variable alongside distraction and morning drowsiness.
, Experimental Researches, 1904supporting
Fatigue, which admittedly in this case was not very great, produced no change in type. The state of drowsiness caused a disturbance of attention which far surpassed the effect of the second external distraction.
Jung differentiates the associative effects of mild fatigue from those of morning drowsiness, showing that drowsiness is the more powerful disruptor of attentional type.
, Experimental Researches, 1904supporting
The associations obtained in fatigue give a result similar to that of a distraction experiment.
Jung summarises a key empirical finding: fatigue and distraction produce comparable associative profiles, suggesting a shared underlying mechanism of attentional disruption.
, Experimental Researches, 1904supporting
this model has been extended to include a system of simultaneous efferent feed-forward and afferent feedback signals that are thought to optimize performance by overcoming fatigue through permitting continuous compensation for unexpected peripheral events.
Paulus situates fatigue within the 'central governor' interoceptive model, where insular cortex integrates afferent signals to modulate performance and counteract peripheral fatigue.
, Treatment approaches for interoceptive dysfunctions in drug addiction, 2013supporting
This 'Story of Wall-Street' is not a tale of de-creation, but rather a story of exhaustion [Erschöpfung].
Han reads Melville's Bartleby as an allegory of the exhaustion endemic to achievement society, distinguishing creative de-creation from the terminal collapse of exhaustion.
, The Burnout Society, 2010supporting
the mind of the primitive man is easily tired… after two hours everybody goes to sleep. They say: we are so tired, can't you finish the palaver?
Jung contrasts the rapid cognitive fatigue of 'primitive' man in sustained deliberation with his extraordinary physical endurance when instinct is engaged, illustrating a dissociation between mental and somatic exhaustion.
, Dream Analysis: Notes of the Seminar Given in 1928-1930, 1984supporting
ego fatigue and, 148–149… self-control depletion. See ego fatigue
Lewis indexes 'ego fatigue' as a distinct mechanism of self-control depletion relevant to addiction, cross-referencing it with dorsolateral PFC disengagement.
, The Biology of Desire: Why Addiction Is Not a Disease, 2015aside
Cognitive fatigue… Multiple sclerosis
Gassner notes cognitive fatigue as a clinically measured outcome in therapeutic climbing research, particularly in multiple sclerosis populations.
, The therapeutic effects of climbing: A systematic review and meta-analysis, 2023aside
not because of the patient's fatigue, but because I considered one hundred reactions enough to analyze.
Jung makes a passing methodological note distinguishing participant fatigue from the researcher's decision to terminate a test series, underscoring attention to confounding in experimental design.
, Experimental Researches, 1904aside