Why Am I So Tired All the Time?
A UK Pharmacist Explains the Most Common Causes of Ongoing Fatigue
Quick reassurance: Feeling tired is normal. Feeling exhausted all the time is not.
If you’ve found yourself asking, “Why am I so tired all the time?” you’re not alone. Persistent fatigue is one of the most common health concerns in the UK.
If you’re waking up unrefreshed, struggling through the afternoon, or relying on caffeine just to function, you’re not alone. As a Pharmacist Prescriber, this is something I discuss with patients every week. Often, there is a clear reason. Sometimes, there are several.
The key is not guessing — but understanding what your body may be trying to tell you.
Common patterns we hear
“I’m sleeping, but I’m not refreshed.”
“My afternoons are a write-off.”
“I’m fine until I stop — then I crash.”
If symptoms are persistent or affecting daily life, targeted testing can often give clarity — or reassurance. Our team can advise on the tests we provide and help you choose.
Choose a time that suits you.
First: What Counts as “Persistent Fatigue”?
Occasional tiredness happens to everyone. Poor sleep, a busy week, stress at work — these can all leave you drained.
Persistent fatigue is different. It usually:
- Lasts more than a few weeks
- Does not improve with rest
- Affects your mood or motivation
- Interferes with daily life
Tip: If tiredness has become your “normal”, a quick check of iron, vitamin D, thyroid, B12 and blood sugar can often provide answers — or reassurance.
1. Iron Deficiency (With or Without Anaemia)
Iron helps your red blood cells carry oxygen around the body. When iron levels are low, your tissues don’t get enough oxygen. That’s when fatigue sets in.
Common symptoms include:
- Extreme tiredness
- Pale skin
- Breathlessness on exertion
- Hair thinning
- Headaches
- Restless legs
Many people assume iron deficiency always means anaemia. It doesn’t. Your iron stores (measured by ferritin) can be low before anaemia develops.
In the UK, iron deficiency is common in:
- Women with heavy periods
- People following plant-based diets
- Those with digestive conditions
- After illness or surgery
A simple blood test can assess ferritin and haemoglobin levels.
2. Vitamin D Deficiency (Very Common in the UK)
Vitamin D plays a role in immune health, muscle strength and mood regulation.
Because sunlight is limited for much of the year in the UK, low levels are extremely common.
Symptoms may include:
- Ongoing tiredness
- Low mood
- Muscle aches
- Bone discomfort
- Frequent infections
Many people feel better once levels are corrected — but it’s important not to supplement blindly at high doses without knowing your starting point.
![“Pharmacist discussing fatigue blood test results in a UK clinic”](https://thehealthdispensary.co.uk/wp-content/uploads/2026/03/15-minute-blood-test-consult.jpeg")
3. Underactive Thyroid (Hypothyroidism)
Your thyroid gland controls your metabolism. When it becomes underactive, everything slows down.
Symptoms often develop gradually and can include:
- Weight gain
- Feeling cold
- Constipation
- Dry skin
- Brain fog
- Heavy or irregular periods
- Persistent fatigue
Because symptoms overlap with stress and ageing, thyroid issues can go unnoticed for months.
A TSH blood test is the standard first check.
4. Vitamin B12 Deficiency
Vitamin B12 supports nerve health and red blood cell production.
Low levels can cause:
- Fatigue
- Tingling in hands or feet
- Memory problems
- Mood changes
- Sore tongue
B12 deficiency is more common in vegetarians, vegans, and people with certain digestive conditions.
Unlike iron deficiency, neurological symptoms can occur even before blood counts change significantly.
5. Blood Sugar Imbalance
Fluctuating or raised blood sugar levels can cause energy crashes.
You might notice:
- Afternoon slumps
- Increased thirst
- Frequent urination
- Slow wound healing
- Blurred vision
An HbA1c blood test measures average blood sugar levels over three months and can identify pre-diabetes or diabetes.
Little reality check: symptoms overlap a lot. If you’ve been guessing for months, a small set of targeted tests can save a lot of time (and a lot of Googling).
6. Hormones and Perimenopause
For women in their late 30s, 40s and early 50s, hormones often play a part.
Perimenopause can cause:
- Fatigue
- Sleep disturbance
- Anxiety
- Brain fog
- Heavy or irregular periods
Iron deficiency and thyroid issues can exist alongside hormonal changes, which is why symptoms should not automatically be attributed to “just hormones”.
7. Stress, Sleep and Modern Life
Not every cause of fatigue shows up in blood tests.
Chronic stress increases cortisol levels. Over time, this can disrupt sleep, appetite and energy regulation.
Poor sleep quality — even if you are in bed for 8 hours — can leave you feeling drained.
Common contributors include:
- Late-night screen use
- Shift work
- Alcohol
- Anxiety
- Sleep apnoea
Blood tests cannot fix lifestyle factors — but they can rule out underlying medical causes.
8. Medication Side Effects
Some medicines can contribute to fatigue, including:
- Certain antihistamines
- Beta-blockers
- Antidepressants
- Some blood pressure medications
If you suspect medication is contributing, speak to your pharmacist or GP before making changes.
When should you see a GP urgently?
Seek urgent advice if fatigue is accompanied by:
- Unintentional weight loss
- Persistent night sweats
- Ongoing unexplained pain
- Chest pain
- Significant breathlessness
- Swollen lymph nodes
- Fatigue worsening rapidly
When Are Blood Tests Helpful?
Because symptoms overlap, guessing rarely works.
Targeted blood tests can check:
- Iron levels
- Vitamin D
- Thyroid function
- Vitamin B12
- Blood sugar markers
Testing can either identify a clear cause — or provide reassurance that levels are normal, allowing focus on sleep, stress and lifestyle instead.
As a Pharmacist Prescriber, I often advise patients that testing is most helpful when symptoms are persistent, unexplained, or affecting quality of life.
Where can I get a blood test in Neath?
At The Health Dispensary, we offer convenient 15-minute blood tests in our clinic. Appointments are calm, professional and private.
We provide: clear explanation of results, a printed report, follow-up advice, and guidance on whether GP referral is needed.
If you are unsure which test is appropriate, you can book a short call first.
Frequently Asked Questions
Is it normal to feel tired every day?
No. Occasional tiredness is normal. Daily exhaustion that affects function should be explored.
For further guidance, the NHS provides advice on persistent tiredness: NHS: Tiredness and fatigue
Can stress alone cause fatigue?
Yes. Chronic stress can significantly affect sleep and energy levels.
Should I take supplements without testing?
Low-dose vitamin D in winter is common in the UK. However, high-dose supplementation should ideally follow testing.
How long should fatigue last before checking it?
If it persists beyond a few weeks or affects daily life, it is reasonable to investigate.
Author
Ali Sparkes, MPharm IP
Superintendent Pharmacist & Independent Prescriber, The Health Dispensary
With decades of experience in community pharmacy, a qualified wellness coach, and a multi-UK award winner, Ali works closely with patients to understand the root causes of symptoms and support meaningful, lasting improvements in health.
