Subjective fatigue: molecular mechanisms & dependencies

How nutrients influence it

Every nutrient with a recorded effect on this component, credited to the nutrient that acted rather than the chapter that recorded it. Open a nutrient to see the findings and the conditions they were measured under.

Human evidence only

How nutrients reach it in more than one step

Chains of two or more recorded steps that end here, grouped by the nutrient they start from. Each step is a separate finding, so a chain is a route a mechanism could take, not proof that it does.

Tracing routes…

What it does

Every recorded relationship this component is part of, grouped by its role. Plain wording comes first; the technical statement follows.

Recorded relationships

What acts on it

Tolerance occurred on subjective measures but not the measured physiological endpoints; chronic effects remained mainly on EEG beta-2 power.
Caffeine → Subjective fatigue source_derived_draftungraded
Experimental context and source evidence
evidence_access
Primary abstract
experimental_model
16 regular users; double-blind within-subject study; at least 14 days on 400 mg/day or placebo, with acute challenges.
limitations
No universal claim that caffeine never benefits performance; these results concern the selected outcomes and schedule.
nutrient_topic
Caffeine collection; salts, coffee, species and coexposure contexts retain their identities. · Caffeine
plain_language
Feeling tolerant did not mean every measured response had disappeared.
primary_references
Caffeine withdrawal, acute effects, tolerance, and absence of net beneficial effects of chronic administration: cerebral blood flow velocity, quantitative EEG, and subjective effects. · 2009 · https://pubmed.ncbi.nlm.nih.gov/19241060/ · DOI 10.1007/s00213-009-1489-4
Caffeine: receptors, metabolism, nutrient interactions, adaptation and discovery questions (2026-09-18) · lines 140–146
AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · 16 regular users; double-blind within-subject study; at least 14 days on 400 mg/day or placebo, with acute challenges. · source_derived_draft · unverified_draft
## caf-tolerance Feeling tolerant did not mean every measured response had disappeared. Tolerance occurred on subjective measures but not the measured physiological endpoints; chronic effects remained mainly on EEG beta-2 power. Model: 16 regular users; double-blind within-subject study; at least 14 days on 400 mg/day or placebo, with acute challenges. Limitations: No universal claim that caffeine never benefits performance; these results concern the selected outcomes and schedule. Evidence access: Primary abstract Caffeine withdrawal, acute effects, tolerance, and absence of net beneficial effects of chronic administration: cerebral blood flow velocity, quantitative EEG, and subjective effects. · 2009 · https://pubmed.ncbi.nlm.nih.gov/19241060/ · DOI 10.1007/s00213-009-1489-4
Complete structured claim and evidence
Withdrawal increased tiredness/fatigue ratings and decreased energy/vigor ratings.
Acute withdrawal after repeated caffeine exposure → Subjective fatigue source_derived_draftungraded
Experimental context and source evidence
evidence_access
Primary abstract
experimental_model
16 regular users; double-blind within-subject study; at least 14 days on 400 mg/day or placebo, with acute challenges.
limitations
Withdrawal is adaptation to repeated exposure, not an essential-nutrient deficiency. Blood-flow velocity is not absolute cerebral perfusion.
nutrient_topic
Caffeine collection; salts, coffee, species and coexposure contexts retain their identities. · Caffeine
plain_language
Stopping after repeated use produced a measurable response.
primary_references
Caffeine withdrawal, acute effects, tolerance, and absence of net beneficial effects of chronic administration: cerebral blood flow velocity, quantitative EEG, and subjective effects. · 2009 · https://pubmed.ncbi.nlm.nih.gov/19241060/ · DOI 10.1007/s00213-009-1489-4
Caffeine: receptors, metabolism, nutrient interactions, adaptation and discovery questions (2026-09-18) · lines 132–138
AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · 16 regular users; double-blind within-subject study; at least 14 days on 400 mg/day or placebo, with acute challenges. · source_derived_draft · unverified_draft
## caf-withdraw-fatigue Stopping after repeated use produced a measurable response. Withdrawal increased tiredness/fatigue ratings and decreased energy/vigor ratings. Model: 16 regular users; double-blind within-subject study; at least 14 days on 400 mg/day or placebo, with acute challenges. Limitations: Withdrawal is adaptation to repeated exposure, not an essential-nutrient deficiency. Blood-flow velocity is not absolute cerebral perfusion. Evidence access: Primary abstract Caffeine withdrawal, acute effects, tolerance, and absence of net beneficial effects of chronic administration: cerebral blood flow velocity, quantitative EEG, and subjective effects. · 2009 · https://pubmed.ncbi.nlm.nih.gov/19241060/ · DOI 10.1007/s00213-009-1489-4
Complete structured claim and evidence

The events it takes part in

A mechanism often involves more than two components. These are the full events, with every participant and its role.

Situations it appears in

Low-supply and faulty-machinery situations recorded in the chapters where this component plays a part.

In the sources

Preserved passages that mention this component, quoted exactly. Open one to read it in context.

Open hypotheses

Proposed ideas that involve this component. They are labeled as hypotheses and do not change any recorded statement.

This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.

Subjective fatigue