Why am I always tired?

Why tiredness deserves a real answer

If you’ve searched “why am I always tired?”, you’ve probably already been told it’s stress, dehydration, or you should just sleep more. Sometimes that’s true. Often it isn’t the whole story.

Persistent tiredness affects work, relationships, mood, and quality of life. It’s also a symptom of several treatable medical conditions that can be picked up with a focused blood test and a proper conversation. The trick is asking the right questions and ordering the right tests — not a 60-marker private “wellness panel” that comes back with 12 minor abnormalities and no plan.

Here’s the framework we actually use in clinic.

The clinical framework

When someone comes in saying “I’m tired all the time,” we’re thinking through five buckets in parallel:

1. Lifestyle — sleep, exercise, diet, alcohol, caffeine, screen time, work pattern
2. Medical (physical) — thyroid, iron, vitamin D, diabetes, kidney/liver, sleep apnoea, infections
3. Mental health — depression, anxiety, burnout, grief, ADHD (often missed)
4. Medications — many drugs cause fatigue; sometimes the answer is in the prescription
5. Red flags — weight loss, night sweats, blood in stool, persistent fevers — these change everything

The key insight is that tiredness is rarely from a single cause. It’s usually a combination — mediocre sleep + iron at the low end of normal + chronic stress + a bit too much wine = exhausted human. Treating just one factor often makes a noticeable difference.

Lifestyle causes

If we’re being honest, the majority of tiredness has a lifestyle root. That doesn’t mean it’s your fault, or that we dismiss it. It means it’s often the most fixable layer.

Sleep quantity AND quality

Adults need 7–9 hours. Getting 6 every weeknight catches up with you, no matter how good you feel on caffeine. But quantity isn’t the whole story:

• Sleep apnoea is grossly underdiagnosed — particularly in middle-aged men, post-menopausal women, and anyone who snores or wakes unrefreshed.
• Alcohol destroys sleep quality. Two glasses of wine in the evening fragments the second half of the night.
• Screen time before bed, irregular sleep timing, late caffeine — all measurable contributors.

Exercise paradox

Too little is bad. Too much also is. People doing high-intensity training daily while sleeping poorly and not eating enough are often exhausted. Overtraining is real. Inactivity is more common.

Caffeine and stimulants

If you need 4 coffees to function, you’re probably not actually awake — you’re masking something. The honest test: a 2-week reduction. Headaches for the first week, then you find out what your baseline energy actually is.

Hydration, nutrition, blood sugar

Boring but real. Skipping breakfast, low-protein lunches, big carb dinners — produces energy peaks and crashes. Not every diet works for every person, but the basics of regular eating with protein, fibre, and moderate carbohydrates make a noticeable difference for most.

Medical causes worth ruling out

This is where the “just sleep more” advice fails. There are a small number of conditions that genuinely cause tiredness and need treating.

Iron deficiency

Affects around 1 in 5 menstruating women and a smaller proportion of men. Causes fatigue, breathlessness on stairs, hair thinning, restless legs. We test ferritin (iron stores) and full blood count. More on iron deficiency →

Thyroid problems

Underactive thyroid (hypothyroidism) causes fatigue, weight gain, cold intolerance, low mood, dry skin, slow thinking. A simple blood test picks this up. More on thyroid →

Vitamin D deficiency

Very common in the UK, particularly in winter, indoor workers, and people with darker skin. Contributes to fatigue, muscle aches, low mood. More on vitamin D →

B12 deficiency

Particularly in vegetarians/vegans, older adults, people on long-term acid-suppressing medication, or those with absorption problems. Causes fatigue, neurological symptoms, low mood.

Diabetes

Tiredness, thirst, frequent urination, blurred vision — or sometimes just tiredness. Checked with HbA1c (a single blood test reflecting average sugar over 3 months).

Sleep apnoea

Snoring + daytime sleepiness + waking unrefreshed = probable sleep apnoea until proven otherwise.

Less common but worth thinking about

• Coeliac disease — sometimes presents only with fatigue and anaemia
• Adrenal problems (rare but missed)
• Heart failure — in older adults or those with breathlessness on exertion
• Autoimmune conditions like lupus, rheumatoid arthritis
• Cancer — particularly with weight loss, night sweats, or other red flags

Mental health causes

Depression doesn’t always look like sadness. Often it looks like exhaustion, loss of interest, difficulty getting started, sleeping badly or sleeping too much. Around a quarter to a third of people who come to a GP saying “I’m tired” have an underlying mental health driver they haven’t named.

Anxiety burns through energy. Burnout — the specific exhaustion from prolonged unsustainable stress — is a recognised phenomenon and looks medical, but the treatment is different.

Often-missed: undiagnosed adult ADHD. The relentless effort of compensating for executive function challenges in a neurotypical world is exhausting. Many adults presenting with chronic tiredness, particularly women, have undiagnosed ADHD. More on adult ADHD →

Which tests are actually useful

A sensible blood panel for unexplained tiredness:

• Full blood count — anaemia, infection, blood disorders
• Ferritin — iron stores
• TSH and free T4 — thyroid
• Vitamin D
• B12 and folate
• HbA1c — diabetes screening
• Kidney function (U&E)
• Liver function
• Calcium
• CRP or ESR — inflammation marker

Add specific tests based on history: coeliac antibodies if any digestive symptoms; ANA if joint pains/rashes; cortisol if specific features of adrenal disease.

What we don’t do: order a 100-marker “wellness panel” that flags every result one standard deviation from average. That produces anxiety, false positives, and no actual answers.

Red flags — don’t miss these

See a doctor promptly (not just for general fatigue advice) if tiredness comes with any of:

• Unexplained weight loss
• Night sweats (drenching, regular)
• Persistent fevers
• Blood in stool, urine, or coughed up
• Lumps that are new or growing
• Breathlessness that’s new or worse
• Chest pain on exertion
• Severe headaches that are new or different
• Confusion, balance problems, weakness
• Major mood changes, thoughts of self-harm

What to do next

If you’ve been tired more than 6 weeks with no obvious cause:

1. Track it. Two weeks of brief notes on sleep, alcohol, exercise, diet, mood, and energy level (0–10) is genuinely useful. You may spot a pattern you didn’t notice.
2. Address the low-hanging fruit. Sleep regularity, reduced alcohol, basic exercise. Most people see at least some improvement.
3. Get the right blood tests. See your GP or come to us. A focused panel beats a scattered one.
4. Don’t accept “just stress” as a final answer. Stress is often part of it, but it’s rarely the whole story.

If you’d like to come in, we offer 30-minute consultations with proper history-taking, examination, and a tailored blood panel. See our chronic fatigue page for more on the diagnostic process.