Always Tired: Working Through the Causes of Chronic Fatigue

“I’m always tired” is one of the most frequent complaints in general practice and one of the most poorly worked up, because it is vague, has dozens of causes, and tends to be met either with a vitamin prescription or with reassurance. A systematic approach usually finds the answer.

First, define it

Sleepiness means a tendency to doze off. It points to sleep disorders, especially sleep apnoea.

Fatigue means lack of energy and motivation without necessarily falling asleep. Points to medical, psychological and lifestyle causes.

Weakness means genuine loss of muscle power. Points to neurological, muscular or metabolic disease and is the most concerning of the three.

People use the words interchangeably; the distinction narrows the search considerably.

Lifestyle causes, which account for most cases

• Insufficient sleep. The commonest cause by far. Most adults need seven to nine hours; many consistently get six
• Irregular sleep timing and weekend shifts in schedule
• Poor sleep quality from caffeine late in the day, alcohol, screens, noise or an uncomfortable environment
• Physical inactivity, which causes deconditioning and, paradoxically, more fatigue
• Dehydration
• Erratic eating, skipped meals, very low calorie dieting
• Chronic stress and lack of recovery time
• Overwork without rest days
• Excess caffeine, which fragments sleep and creates a dependence cycle
• Alcohol, which reliably degrades sleep quality

Medical causes worth testing for

• Anaemia, particularly iron deficiency, and especially in menstruating women
• Vitamin B12 deficiency, common in vegetarians
• Vitamin D deficiency
• Hypothyroidism
• Diabetes, both undiagnosed and poorly controlled
• Obstructive sleep apnoea, which is massively under-diagnosed and should be considered in anyone who snores, is overweight, or wakes unrefreshed
• Chronic kidney disease
• Liver disease
• Chronic infection: tuberculosis, hepatitis, HIV
• Coeliac disease
• Heart failure
• Chronic obstructive pulmonary disease
• Adrenal insufficiency, uncommon but important
• Cancer, particularly with weight loss, night sweats or other red flags
• Autoimmune disease: rheumatoid arthritis, lupus, inflammatory bowel disease
• Restless legs syndrome, which fragments sleep
• Post-viral fatigue, including after dengue, influenza and COVID-19
• Menopause, through sleep disruption and hormonal change

Psychological causes

Depression is among the most common causes of fatigue and frequently presents as tiredness rather than sadness, particularly in men and in older adults. Key clues are loss of interest and pleasure, early morning waking, guilt, poor concentration and appetite change.

Anxiety is exhausting through constant physiological arousal and disturbed sleep.

Burnout has its own pattern: emotional exhaustion, cynicism about work and reduced sense of accomplishment.

These are not lesser explanations than physical ones, and they respond to treatment.

Medications that cause fatigue

Beta blockers, some antihypertensives, antihistamines including older ones in cold remedies, antidepressants, antipsychotics, benzodiazepines, opioids, muscle relaxants, statins occasionally, and antiepileptics. A medication review is one of the highest-yield steps and is often skipped.

A sensible first round of tests

• Complete blood count
• Ferritin and iron studies
• Vitamin B12 and folate
• Vitamin D
• Thyroid function
• Fasting glucose or HbA1c
• Kidney and liver function
• Electrolytes and calcium
• CRP or ESR
• Coeliac serology where there are digestive symptoms
• Urinalysis
• Sleep apnoea screening questionnaire
• A depression screening tool

Resist the urge to order an enormous panel. Incidental abnormalities generate anxiety and investigations far more often than they explain fatigue.

Red flags needing prompt assessment

• Unexplained weight loss
• Night sweats
• Fever
• Lymph node enlargement
• Breathlessness or chest pain
• Genuine muscle weakness rather than tiredness
• Blood in stool or urine
• A new lump
• Fatigue in someone with a cancer history
• Rapid onset over days
• Severe fatigue preventing normal function

Myalgic encephalomyelitis and chronic fatigue syndrome

A diagnosis of exclusion involving at least six months of fatigue, post-exertional malaise where symptoms worsen disproportionately after activity and recovery takes more than a day, unrefreshing sleep, and cognitive difficulty or orthostatic intolerance.

Post-exertional malaise is the defining feature and distinguishes it from ordinary fatigue. Management focuses on pacing and activity management within an energy envelope, rather than graded increases, which can worsen the condition.

What usually helps

Fix the sleep first, because almost nothing else works while sleep is inadequate. Then establish regular meals, build activity gradually rather than ambitiously, moderate caffeine and alcohol, get daylight in the morning, treat any deficiency found, address mood, and review medications.

Vitamin injections and energy tonics are the most commonly given and least useful response to fatigue in the absence of a demonstrated deficiency.

This is general information. Fatigue lasting more than a few weeks, or with any red flag above, deserves a proper medical assessment rather than a supplement.