Tired All the Time? Why Fatigue Happens and What to Check

In 30 seconds

• Being tired occasionally is normal. Unexplained tiredness lasting for weeks or affecting daily life deserves attention.
• Poor sleep, stress, under-eating, an unbalanced diet, dehydration, alcohol and some medicines can all reduce energy.
• Iron deficiency anaemia, vitamin B12 deficiency, thyroid disease, diabetes and sleep apnoea are among the medical causes that can produce fatigue.
• Feeling tired does not tell you which nutrient — if any — is low.
• Taking extra iron, B12, magnesium or other supplements when you do not need them is not the same as correcting a genuine deficiency.
• The pattern matters: tired + breathless is different from tired + thirsty, tired + snoring, or tired + pins and needles.
• There is no single universal “fatigue blood test”. Testing should be guided by symptoms, history and risk factors.
• Some people have a more complex fatigue pattern, including Long COVID or ME/CFS, where simply “pushing through” can be inappropriate.
• HTMA can add nutritional context but cannot diagnose the medical cause of persistent fatigue.

What do we actually mean by “tired”?

People use the word “tired” to describe several different experiences.

You might mean:

• Sleepy
• Physically weak
• Mentally exhausted
• Unmotivated
• Drained after small amounts of activity
• Unable to concentrate
• Heavy-legged
• Exhausted despite sleeping
• Fine in the morning but depleted by afternoon
• Constantly wanting to lie down

Those are not necessarily the same thing.

Someone who falls asleep at their desk may have a different problem from somebody whose muscles feel weak, or somebody who wakes exhausted after eight hours in bed.

The clues hidden in your other symptoms

Fatigue on its own is extremely non-specific.

The symptoms travelling with it can sometimes point towards useful questions.

Tired + short of breath + palpitations + pale skin

Iron deficiency anaemia becomes one possibility worth investigating.

Tired + pins and needles + brain fog or a sore tongue

Vitamin B12 deficiency may need consideration.

Tired + feeling cold + constipation + weight gain

An underactive thyroid is one possible explanation.

Tired + very thirsty + urinating frequently + unexplained weight loss

Diabetes needs to be considered.

Tired during the day + loud snoring + choking or gasping at night

Sleep apnoea should be taken seriously.

Tired + persistent low mood, anxiety or overwhelming stress

Mental and emotional health may be contributing.

Tired + symptoms that become markedly worse after activity

That pattern deserves more careful assessment, particularly if the worsening is delayed and recovery takes unusually long.

Iron: one of the first nutritional questions worth asking

Iron is needed to make haemoglobin, the protein in red blood cells that carries oxygen around the body.

When iron deficiency becomes severe enough to cause anaemia, common symptoms can include:

• Tiredness
• Lack of energy
• Breathlessness
• Palpitations
• Headaches
• Paler skin

Some people also experience restless legs, hair loss or unusual cravings such as wanting to chew ice.

But why is the iron low?

This is just as important as correcting it.

Possible explanations can include:

• Heavy menstrual bleeding
• Pregnancy
• Low dietary intake
• Gastrointestinal blood loss
• Problems absorbing iron
• Other medical causes

Does eating more iron-rich food help?

Diet matters.

Useful sources include:

• Meat
• Poultry
• Fish
• Beans and lentils
• Fortified cereals
• Nuts and seeds
• Green leafy vegetables

Plant-based iron is absorbed less efficiently than haem iron from animal foods.

Eating vitamin-C-rich foods with plant sources of iron can improve absorption.

Food alone may not be enough to correct established iron-deficiency anaemia. That depends on severity and cause. If iron deficiency is confirmed, appropriate treatment and investigation should be guided clinically.

Vitamin B12: fatigue can occur even without obvious anaemia

Vitamin B12 helps the body make healthy red blood cells and supports normal neurological function.

Deficiency can cause:

• Extreme tiredness
• Lack of energy
• Pins and needles
• Muscle weakness
• Problems with memory or concentration
• Balance problems
• A sore or red tongue

An important point from current NICE guidance is that B12 deficiency should not be ruled out simply because someone does not have anaemia or enlarged red blood cells.

Who may be more vulnerable?

Risk can increase with:

• Pernicious anaemia or autoimmune gastritis
• Some stomach or intestinal surgery
• Malabsorption
• Some medicines
• A vegan diet without reliable B12 supplementation or fortified foods
• Prolonged restrictive diets

Blood testing is the appropriate route when deficiency is suspected.

More B12 is not automatically more energy

Correcting genuine vitamin B12 deficiency can be essential.

But that does not mean taking high-dose B12 gives everybody more energy.

A placebo-controlled trial in people with fatigue but normal B12 levels found no meaningful improvement in fatigue from surplus B12 supplementation.

Deficiency + replacement is one question. Normal status + extra supplement is another. Advertising often blurs the two.

Could your thyroid be slowing you down?

The thyroid gland helps regulate metabolism.

An underactive thyroid — hypothyroidism — can cause symptoms including:

• Significant fatigue
• Feeling unusually cold
• Weight gain
• Constipation
• Difficulty concentrating
• Low mood
• Dry skin or hair changes
• Heavy or irregular periods

The symptoms can develop gradually.

That matters because people sometimes adjust to feeling progressively worse and assume the tiredness is simply age, work or stress. Thyroid function can be assessed with blood tests when appropriate.

What about blood sugar?

Very high blood glucose can make somebody feel tired.

Symptoms that deserve attention include:

• Persistent thirst
• Urinating more frequently
• Fatigue
• Unexplained weight loss
• Blurred vision
• Slow-healing wounds
• Recurrent infections

Type 2 diabetes can develop gradually, and some people have few or no obvious symptoms.

Could poor sleep be the real problem?

Someone can spend eight hours in bed without getting eight hours of restorative sleep.

One condition deserves particular attention here:

Sleep apnoea

Obstructive sleep apnoea causes the airway to narrow or close repeatedly during sleep.

Possible clues include:

• Loud snoring
• Breathing pauses witnessed by another person
• Choking or gasping
• Frequent waking
• Morning headaches
• Difficulty concentrating
• Severe daytime tiredness

You may not know it is happening because you are asleep.

Stress can make you genuinely exhausted

Physical and psychological health are not separate machines.

Chronic stress can affect:

• Sleep
• Appetite
• Muscle tension
• Concentration
• Motivation
• Physical activity
• Digestion
• Alcohol or caffeine intake

The result can be very real fatigue.

Anxiety and depression can also present with tiredness, poor sleep, reduced concentration and low motivation. Recognising this does not mean dismissing symptoms as “all in your head”. It means acknowledging another possible route to feeling exhausted.

Menopause can enter the picture too

During perimenopause and menopause, tiredness may arise through several pathways.

These can include:

• Disrupted sleep
• Night sweats
• Hot flushes
• Mood changes
• Increased stress
• Changes in activity and body composition
• Heavy or irregular bleeding during perimenopause, which can sometimes contribute to iron deficiency

Again, “fatigue in menopause” is not one single mechanism. The surrounding symptoms matter.

Are you actually eating enough?

Not every nutritional fatigue problem is a micronutrient deficiency.

Sometimes the body simply does not have enough fuel.

This can happen with:

• Aggressive dieting
• Skipping meals
• Very low carbohydrate intake in some people
• Poor appetite
• Illness
• Highly restrictive diets
• Intense exercise without adequate food
• Rapid weight loss

Someone using an appetite-reducing medicine such as a GLP-1 treatment may also find that total food intake falls dramatically.

Smaller portions still need to provide enough:

• Protein
• Carbohydrate
• Essential fats
• Vitamins and minerals
• Fluids

Could dehydration make you tired?

Yes.

Even relatively modest dehydration can make some people feel tired, headachy, dizzy or less able to concentrate.

Fluid needs vary with body size, climate, physical activity, illness and diet.

The caffeine trap

Caffeine can temporarily make us feel more alert.

That can create a cycle:

People vary considerably in how quickly they metabolise caffeine. Energy borrowed from tomorrow is not always free.

What about medicines?

Some medicines can contribute to tiredness or sleepiness.

Examples can include certain:

• Antihistamines
• Pain medicines
• Antidepressants
• Blood-pressure medicines
• Sedatives
• Anti-anxiety medicines
• Epilepsy medicines

This varies enormously between drugs and individuals.

Do not stop prescribed medication because you feel tired. Ask whether fatigue could be a side effect and whether the medicine or dose needs reviewing.

Sometimes the body is recovering from illness

Fatigue commonly accompanies infections.

For most people it improves as recovery progresses.

But some people experience prolonged symptoms after an infection.

Long COVID

Fatigue is one of the most commonly reported symptoms of Long COVID.

For some people it is profound and persistent.

The science is still evolving, and there is currently no simple supplement or single medicine that reliably eliminates Long-COVID fatigue.

Is being very tired the same as ME/CFS?

No.

ME/CFS is not simply “being tired for a long time”.

NICE describes a much more specific pattern. Features include:

• Debilitating fatigue
• Substantial reduction in previous activity
• Unrefreshing sleep or sleep disturbance
• Cognitive difficulties or “brain fog”
• Post-exertional malaise

Post-exertional malaise means symptoms become worse after physical, cognitive, emotional or social activity.

The worsening may be delayed by hours or even days and recovery can take a long time.

Should I take an “energy” supplement?

Not simply because you feel tired.

Products marketed for energy can contain combinations of:

• B vitamins
• Magnesium
• Iron
• Caffeine
• Herbal extracts
• Amino acids
• Adaptogens

Some ingredients may have legitimate uses.

But putting many ingredients into one product does not establish which one you need.

Iron

Do not routinely take high-dose iron without a reason. Too much iron can be harmful, and unexplained iron deficiency may need investigation.

Vitamin B12

Essential if deficient. Not proven to turn a person with normal B12 status into a high-energy version of themselves.

Magnesium

Magnesium is physiologically important, but tiredness alone does not establish magnesium deficiency.

Vitamin D

Vitamin D deficiency should be corrected when present. But fatigue is too non-specific to diagnose vitamin D deficiency from symptoms alone.

Stimulants

Caffeine can increase alertness. It does not treat anaemia, hypothyroidism, diabetes, sleep apnoea, B12 deficiency or ME/CFS.

Would testing help?

If fatigue persists for several weeks, affects daily life or is accompanied by other symptoms, clinical assessment may be appropriate.

There is no single universal “fatigue panel” that everybody needs.

Testing should follow the history.

Depending on the circumstances, clinicians may consider investigations such as:

• Full blood count
• Ferritin or other iron studies
• Vitamin B12 and folate
• Thyroid function
• HbA1c or blood glucose
• Kidney function and electrolytes
• Liver function
• Inflammatory markers
• Calcium
• Coeliac screening
• Vitamin D in selected circumstances
• Other tests suggested by the history

Sometimes the most useful “test” is not blood at all.

If sleep apnoea is suspected, a sleep study may be more relevant.

A normal blood test does not mean your symptoms are imaginary

Routine blood tests are designed to look for particular problems.

They cannot measure every possible explanation for fatigue.

Where can HTMA fit?

Hair Tissue Mineral Analysis measures minerals found in a sample of newly grown hair.

It can provide another type of nutritional information.

But persistent fatigue is a good example of why the boundaries need to be clear.

It should not replace blood tests, sleep assessment or medical investigation when those are needed.

HTMA may instead add nutritional context.

Questions it may contribute to include:

• What mineral patterns are present in the hair sample?
• How do those patterns sit alongside the person's diet and supplements?
• Is the person taking multiple minerals without a clear rationale?
• Are there broader nutritional questions worth exploring?
• On a later repeat test, has the hair mineral pattern changed?

The distinction remains: HTMA may add context. It should not be used to explain away unexplained fatigue.

Learn More About HTMA

What is new right now? — August 2026

Fatigue research is increasingly showing why “one cause, one pill” is the wrong model.

Different forms of fatigue may arise from very different biological processes.

We will update this page as important fatigue research develops.

What we know — and what we do not

What we know

Persistent fatigue can be associated with:

• Inadequate or disrupted sleep
• Iron deficiency and anaemia
• Vitamin B12 deficiency
• Thyroid disease
• Diabetes
• Sleep apnoea
• Stress, anxiety or depression
• Menopause
• Medicines
• Infection and post-viral illness
• ME/CFS
• Inadequate dietary intake
• Many other medical conditions

What we cannot know from the word “tired”

We cannot tell:

• Whether iron is low
• Whether vitamin B12 is low
• Whether magnesium is low
• Whether thyroid function is abnormal
• Whether blood sugar is high
• Whether somebody has sleep apnoea
• Whether the fatigue is nutritional at all

When should tiredness be checked?

The NHS advises seeing a GP when tiredness has lasted for a few weeks and you do not know why, or when it is affecting your daily life.

Assessment is also particularly sensible when fatigue occurs with symptoms such as:

• Unexplained weight loss
• Significant mood changes
• Shortness of breath
• Palpitations
• Persistent thirst
• Increased urination
• Loud snoring or choking during sleep
• Neurological symptoms
• Persistent bowel symptoms
• Abnormal bleeding

What can you do now?

1. Describe the pattern.
   When did the fatigue begin? Is it constant? Are you sleepy or physically weak? Do you wake refreshed? Does activity improve or worsen it? Did it begin after illness?
2. Audit your sleep.
   Consider bedtime, waking time, snoring, breathing pauses, night waking, caffeine, alcohol, screens and shift work.
3. Audit your food.
   Ask whether you regularly get enough total food, protein, vegetables and fruit, wholegrains, beans and pulses, iron-rich foods and reliable vitamin B12 if eating a plant-based diet.
4. Review what you take.
   Make a list of prescribed medicines, over-the-counter medicines, vitamins, minerals, herbal supplements, energy drinks and caffeine.
5. Do not ignore persistent unexplained fatigue.
   If it continues for weeks or interferes with normal life, investigate rather than continually compensating with caffeine.

How we can help

Persistent fatigue often involves more than one factor.

Nutrition may be central. It may also be only one piece of a wider picture.

Our role is to help examine the nutritional and lifestyle side without pretending that nutrition explains everything.

And HTMA? Where the wider nutritional picture suggests mineral-pattern information could add useful context, HTMA can be considered separately. It does not replace medical assessment or appropriate blood testing.

Research record

First published: 22 August 2026
Last reviewed: 22 August 2026
Latest evidence update: 22 August 2026

Key evidence and guidance

• NHS. Tiredness and fatigue.
• NHS. Iron deficiency anaemia.
• NHS. Vitamin B12 or folate deficiency anaemia.
• NICE. Vitamin B12 deficiency in over 16s: diagnosis and management. NG239.
• NHS. Underactive thyroid (hypothyroidism).
• NHS. Type 2 diabetes.
• NHS. Sleep apnoea.
• NICE. Myalgic encephalomyelitis/chronic fatigue syndrome: diagnosis and management. NG206.
• STIMULATE-ICP Consortium. Efficacy and safety of rivaroxaban, colchicine, and famotidine-loratadine with specialist supportive clinical care for fatigue in patients with post-COVID-19 condition in the UK. Lancet Infect Dis. 2026. PMID 42419335.
• Ramezani E, et al. Effects of B vitamins and magnesium on fatigue, disease activity and quality of life in inflammatory bowel disease. Sci Rep. 2026. PMID 42010310.
• van der Meij BS, et al. Surplus vitamin B12 use does not reduce fatigue in patients with irritable bowel syndrome or inflammatory bowel disease: a randomized double-blind placebo-controlled trial. Clin Nutr ESPEN. 2018. PMID 29460813.