Fatigue and low energy in men: causes, assessment and GP advice

Feeling tired or low in energy is common, but persistent fatigue in men should not be ignored. While stress, poor sleep or lifestyle factors are often involved, ongoing or unexplained fatigue can sometimes indicate an underlying medical issue.

This page explains how GPs assess fatigue in men, common causes, which tests may be considered, and when further review is important.

These articles are intended as educational sources, not diagnostic nor taking place of a proper medical assessment. If you need help, please book an appointment with one of our GP’s.

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What does fatigue mean?

Fatigue is more than just feeling sleepy. Men often describe it as:

Low physical energy
Reduced motivation or drive
Poor concentration or “brain fog”
Reduced exercise tolerance
Feeling drained despite adequate rest

Fatigue can develop gradually and may fluctuate over time.

Seek urgent medical advice if fatigue is accompanied by:

Unintentional weight loss
Persistent fever or night sweats
Chest pain or shortness of breath
New neurological symptoms
Severe or rapidly worsening fatigue

Common causes of fatigue in men

Lifestyle and sleep factors

The most frequent contributors include:

Poor sleep quality or irregular sleep patterns
Long working hours or shift work
Chronic stress
Low physical activity or overtraining
Alcohol use

These factors often overlap and compound each other.

Mental health and wellbeing

Fatigue may be linked to:

Low mood or depression
Anxiety or chronic stress
Burnout

Men may experience fatigue as a physical symptom rather than emotional distress.

Hormonal factors

Hormonal imbalance may contribute to fatigue in some men, including:

Low testosterone
Thyroid dysfunction

Hormones are interpreted alongside symptoms rather than in isolation.

Learn more about Testosterone blood testing here.

Nutritional and metabolic causes

These can include:

Iron deficiency or anaemia
Vitamin B12 or vitamin D deficiency
Poor diet or irregular eating patterns

Medical conditions

Less commonly, fatigue may be associated with:

Inflammatory conditions
Chronic infection
Sleep apnoea
Cardiovascular disease

A careful history helps guide which causes are more likely.

How GPs assess fatigue in men

Assessment usually focuses on:

Duration and pattern of fatigue
Sleep quality and daily routine
Work, stress and mental wellbeing
Exercise levels
Weight changes
Sexual health symptoms
Medication and alcohol use

This context helps decide whether fatigue is likely lifestyle-related or needs further investigation.

Blood tests that may be considered

Blood tests are not always needed, but may be helpful if fatigue is persistent or unexplained. Tests may include:

Full blood count
Thyroid function tests
Iron studies
Vitamin B12 and vitamin D
Blood glucose
Testosterone, when symptoms suggest hormonal involvement

Tests are selected carefully to avoid unnecessary investigations.

Fatigue and testosterone: important context

Low testosterone is not the most common cause of fatigue. Testosterone testing is usually considered when fatigue occurs alongside symptoms such as: