Fatigue Researcher With Decades Of Expertise

On Finding Causes And Treatments For Chronic Fatigue Syndrome (CFS)

Years ago I was writing a book, “Are You Tired of Being Tired?” When I reached about 200 causes, I stopped writing that book.

What Causes Fatigue? Common And Rare Causes Explained

Fatigue occurs when normal physiological processes are disrupted — by infections, inflammation, metabolic changes, nerve sensitisation, or structural problems. Understanding the underlying mechanism is the first step toward effective treatment.

Common Causes Of Fatigue

Fatigue can arise from a wide range of factors. Understanding the root cause helps guide the right treatment.

1. Infections and inflammation — bacterial, viral, or autoimmune triggers activate fatigue
2. Metabolic disturbances — hormonal imbalances, nutrient deficiencies, or blood sugar changes
3. Structural or vascular causes — tissue damage, nerve compression, or circulatory problems
4. Psychological factors — stress, anxiety, and depression can produce measurable physical fatigue
5. Underlying conditions such as Diabetes Type 2, Bronchitis, Pneumonia frequently present with fatigue as a core feature
6. Dangerous fatigue is often linked to acute conditions such as Diabetes Type 2, Bronchitis
7. Vascular emergencies — stroke, pulmonary embolism, heart attack — can present with fatigue
8. Severe infections (sepsis, meningitis) may cause fatigue as a systemic alarm signal
9. Toxic exposures or medication overdose can trigger acute fatigue
10. Trauma or internal injury causing tissue or organ damage
11. Tension and muscle tightness — often relieved by stretching, heat, and relaxation
12. Dehydration — respond to increased fluid intake within 30–60 minutes
13. Stress and anxiety — improved by breathing exercises, mindfulness, and rest
14. Inflammatory processes — NSAIDs or antihistamines can provide relief
15. Positional or ergonomic factors — correcting posture or position resolves fatigue
16. Infectious causes: viral, bacterial, or fungal pathogens triggering systemic or localised fatigue
17. Inflammatory/autoimmune: the body’s immune response producing fatigue as a bystander effect
18. Metabolic: disorders of thyroid, adrenal, or blood glucose regulation
19. Structural/mechanical: nerve compression, joint damage, or organ enlargement
20. Underlying conditions: Diabetes Type 2, Bronchitis, Pneumonia, Colitis are among the leading identifiable causes
21. Cortisol and adrenaline surges alter inflammation, pain sensitivity, and muscle tension
22. Autonomic dysregulation affects heart rate, digestion, breathing, and vascular tone
23. Psychological hypervigilance amplifies the perception of fatigue
24. Chronic stress disrupts sleep, which independently worsens fatigue
25. Behavioural changes under stress (poor diet, caffeine, inactivity) contribute to fatigue
26. Cortisol nadir at night: cortisol (the body’s natural anti-inflammatory) is lowest at 3–4 AM, allowing inflammation to peak — worsening fatigue in early morning
27. Dehydration during sleep: 6–8 hours without fluid intake concentrates blood and reduces tissue hydration, intensifying fatigue
28. Sleep position: sustained pressure, poor neck or spinal alignment, or restricted circulation overnight amplifies fatigue by morning
29. Inflammatory diseases (rheumatoid arthritis, ankylosing spondylitis): classic morning stiffness and fatigue lasting >30 minutes indicates active inflammation
30. Nocturnal hypoglycaemia or respiratory changes: low blood sugar or mild oxygen desaturation during sleep contributes to morning fatigue
31. Exercise-induced blood flow redistribution: during exertion, blood is diverted to working muscles, which can trigger fatigue in other tissues
32. Dehydration and electrolyte loss: sweat-driven fluid loss increases fatigue particularly in hot environments
33. Lactic acid accumulation and metabolic acidosis: intense exercise generates lactic acid, causing muscle fatigue and systemic effects
34. Post-exercise inflammatory response: micro-tears in muscles trigger a local inflammatory cascade that produces fatigue 12–48 hours later (DOMS)
35. Underlying conditions such as Diabetes Type 2, Bronchitis may be unmasked by the physiological stress of exercise
36. Sympathetic nervous system activation: adrenaline and noradrenaline increase heart rate, muscle tension, and pain sensitivity — all of which worsen fatigue
37. HPA axis activation: cortisol spikes acutely under stress, then becomes dysregulated with chronic stress, driving systemic inflammation
38. Muscle tension: stress causes involuntary clenching and guarding, amplifying musculoskeletal fatigue
39. Hyperventilation: stress-induced breathing changes alter blood CO₂ and pH, contributing to fatigue including dizziness, tingling, and chest tightness
40. Gut-brain axis dysregulation: stress disrupts gastrointestinal motility and microbiome balance, causing or worsening visceral fatigue
41. Acute (minutes to hours): benign causes such as tension, dehydration, hypoglycaemia, or transient vascular changes
42. Subacute (days to 1–2 weeks): infections, post-viral syndromes, minor injuries, or medication effects
43. Prolonged (2–6 weeks): inflammatory responses, subacute infections, or early manifestations of conditions like Diabetes Type 2, Bronchitis
44. Chronic (>6 weeks or recurring): underlying chronic disease, functional disorders, or inadequately treated acute causes
45. Episodic (recurs and remits): migraine, IBS, asthma, anxiety disorders — each episode may be brief but the condition is chronic
46. GP (General Practitioner): first point of contact for all new fatigue — can diagnose common causes and coordinate specialist referral
47. Relevant conditions like Diabetes Type 2, Bronchitis, Pneumonia may require specific specialists for full evaluation
48. If fatigue has a clear systemic pattern, a general internist or hospital physician provides comprehensive assessment
49. For chronic or recurrent fatigue that has resisted primary care treatment, specialist input significantly improves outcomes
50. Emergency department: for sudden, severe, or neurologically associated fatigue that cannot wait for an appointment

What Causes Fatigue? Common and Rare Causes Explained | vHospital, accessed July 31, 2026.