Last updated: October 2026
Most people who feel tired all the time are short on sleep, stressed, low in mood, eating poorly, inactive, or drinking too much alcohol or caffeine. Common medical causes include anaemia, an underactive thyroid, depression, diabetes and fatigue after a virus. The NHS advises seeing a GP if you’ve felt tired for a few weeks and don’t know why.
Doctors often shorten it to TATT, “tired all the time”, and it is a common reason people see their GP. Below: the causes at a glance, what it means if you’re also light-headed, cold or heavy-eyed, a step-by-step plan, the clocks going back, nutrients and blood tests.
Tired all the time: causes at a glance
Most tiredness has an everyday explanation, often two or three at once. Use the clues to narrow it down.
| Cause | Clues | What to do |
|---|---|---|
| Too little or poor-quality sleep | Under 7 hours, waking in the night, unrefreshed in the morning | Fixed wake time, earlier bedtime. See sleep hygiene habits that work |
| Stress, anxiety or low mood | Tired but wired at night, flat by day, losing interest in things | Talk to someone; ask your GP about talking therapy. See tired but wired |
| Lifestyle | Skipped meals, little movement, caffeine to get going, wine to wind down | Follow the step-by-step plan below |
| Anaemia (iron, B12 or folate) | Breathless, pale, palpitations, headaches; heavy periods | Blood test before any iron supplement |
| Underactive thyroid | Feeling cold, weight gain, constipation, dry skin, low mood | Thyroid blood test via your GP |
| Diabetes | Very thirsty, peeing more, weight loss | See your GP for a blood test |
| Sleep apnoea | Loud snoring, gasping at night, sleepy in the day | See your GP. Read sleep apnoea signs |
| After a virus | Started after glandular fever, flu or COVID-19 | Pace yourself; see a GP if it isn’t lifting |
| Medicines | Began after starting a new medicine | Ask your pharmacist; don’t stop prescribed medicine without advice |
| Dark days | Worse from October to March, sleeping more | Morning daylight. See tired after the clocks go back |
Everyday reasons you’re always tired
| Cause | Clues | What helps |
|---|---|---|
| Not enough sleep | Under about 7 hours most nights, late nights, lie-ins | A fixed wake time and earlier bedtime. See revenge bedtime procrastination |
| Poor-quality sleep | Waking often, at 3am, or unrefreshed | See why you wake at 3am and why you wake up tired |
| Stress and burnout | Wired but tired, dreading work | See burnout symptoms |
| Low mood or anxiety | Flat, no motivation, worrying | Talk to someone; see your GP if it lasts. See low mood |
| Caffeine | Relying on coffee, energy drinks | Cut down gradually; none after midday. See caffeine withdrawal |
| Alcohol | Drinking most evenings | Alcohol-free nights. See Dry January |
| Diet | Skipping meals, lots of sugar or ultra-processed food, slumps after lunch | Regular meals with protein, fibre, fruit and vegetables. See tired after eating |
| Too little activity | Sitting most of the day | A daily walk, building up gradually. A short power nap can help on rough days |
| Dark winter days | Worse from October to March | Morning daylight. See winter blues |
Stress and mood matter more than most people expect. In a UK study of 220 people who saw their GP about being tired all the time, most also reported signs of psychological distress. That doesn’t mean it’s “all in your head”: sleep, worry and energy are tightly linked.
Medical causes of tiredness
The NHS lists these conditions as possible causes, with clues to look for. Don’t self-diagnose: see a GP if you’re worried.
| Other symptoms | Possible cause |
|---|---|
| Loud snoring, gasping or choking at night, sleepy in the day | Sleep apnoea |
| Lack of energy, palpitations, shortness of breath, pale skin | Iron deficiency anaemia |
| Very thirsty, peeing more (especially at night), weight loss | Diabetes |
| Feeling cold more than usual, weight gain, constipation, dry skin | Underactive thyroid |
| Restless, nervous, anxious, irritable, muscle weakness | Overactive thyroid |
| Extreme fatigue for at least 3 months, problems thinking, flu-like symptoms | ME/CFS |
Other causes include low vitamin B12 or vitamin D, depression, hormonal changes, some medicines and treatments, and the after-effects of illnesses such as glandular fever or COVID-19. If your tiredness is extreme, has lasted months and gets worse after even small efforts, read our guide to chronic fatigue syndrome (ME/CFS). An underactive thyroid is a common hidden cause, while an overactive thyroid tends to bring restlessness and anxiety with the exhaustion.
More on the two most common deficiencies: iron deficiency symptoms and vitamin B12 deficiency symptoms.
Light-headed and tired all the time
Feeling woozy as well as worn out narrows things down:
- Dehydration. The NHS lists feeling tired, dizzy or light-headed, a headache and dark yellow pee as signs. Drink regularly through the day and aim for pale pee. See how much water you need.
- Low blood pressure. Light-headedness, blurred vision, feeling weak or fainting, often when you stand up quickly. Stand up slowly, drink more water and eat smaller, more frequent meals. Read low blood pressure: what counts as low.
- Anaemia. The NHS lists iron deficiency anaemia among the common causes of dizziness, alongside tiredness, breathlessness and pale skin.
- Low blood sugar. Feeling dizzy, shaky, sweaty, hungry and tired or weak. It mostly affects people with diabetes who take insulin or certain other medicines; in people without diabetes it is rare and needs checking.
- Stress and anxiety. Anxiety can make you dizzy and drain your energy at the same time. See why anxiety makes you dizzy.
See a GP if the dizziness doesn’t go away or keeps coming back, or if it comes with fainting, hearing or speech problems, numbness or weakness, or changes to your eyesight.
Cold and tired all the time
Being cold and tired together is one of the clearer clue pairs:
- Underactive thyroid. The NHS lists “feeling extremely tired” and “feeling cold more than usual” as symptoms, along with weight gain, constipation, low mood and dry skin or hair. A simple blood test checks it.
- Anaemia. Low iron or B12 causes tiredness, breathlessness and pale skin, and is the other common cause to rule out. Worth checking if you have heavy periods or eat little meat.
- Low weight or not eating enough. Being underweight can mean missing out on vitamins and minerals. See a GP if you’ve lost weight without trying.
Our guide to why you’re always cold covers the full list, including circulation problems such as Raynaud’s.
Heavy, tired eyes
Eyes that feel heavy all day usually point to short sleep (see our sleep debt recovery plan), long screen sessions without breaks or dry eyes. See an optician or GP if they aren’t better after a few weeks, and get urgent help for a painful red eye or any sudden change in your vision. For the full list of causes, quick fixes and red flags, read why your eyes feel heavy and tired all the time.
Why am I so tired? Women and men
- Women: heavy periods can lead to iron deficiency anaemia; hormonal changes in pregnancy, perimenopause and menopause commonly disrupt sleep and energy (see the full list of perimenopause symptoms). See perimenopause and sleep and magnesium for women.
- Men: sleep apnoea is more common in men, especially with a larger neck or after drinking. Stress and long hours are frequent drivers. See stress in men.
How to stop feeling tired all the time
Work through these in order for two to three weeks before judging the results. Most are straight from NHS self-help advice for fatigue.
| Step | What to do | Why |
|---|---|---|
| 1. Sleep | Same bedtime and wake time every day, aiming for 6 to 9 hours. Wind down for a couple of hours before bed, no screens in the last hour | A regular rhythm is the single biggest lever |
| 2. Light | Get outside in daylight in the morning, even on grey days | Daylight helps set your body clock |
| 3. Movement | Start with a 10 to 15 minute walk, building towards 150 minutes of moderate activity a week | It sounds odd, but moving more is one of the best ways to feel less tired |
| 4. Caffeine timing | None after midday; if cutting down, do it gradually | Its effects can last up to 7 hours; stopping suddenly causes headaches |
| 5. Alcohol | Several alcohol-free days a week and no more than 14 units | Alcohol makes sleep lighter. See alcohol and sleep |
| 6. Food | Regular meals and healthy snacks every 3 to 4 hours, rather than one big meal | Fewer dips. Ideas: breakfast for energy |
| 7. Hydration | Drink water through the day, more after exercise | Even mild dehydration can make you tired |
| 8. Stress | Build in something relaxing every day; ask your GP about talking therapy if worry or low mood is behind it | Stress and low mood are among the commonest causes |
| 9. When to test | Still tired after a few weeks with no clear reason? Book a GP appointment | Blood tests can rule out anaemia, thyroid problems and diabetes |
For more on the first two steps, see our morning routine for energy and how to fall asleep fast. If you hit a wall mid-afternoon, read about the afternoon slump.
Tired after the clocks go back
The clocks go back an hour at 2am on Sunday 25 October 2026. It’s sold as an extra hour in bed, but a research review found little evidence of extra sleep that night, and earlier waking over the following days can mean a net loss of sleep across the week.
- Keep your wake time. Get up at your usual time on Sunday and all week, rather than sleeping in.
- Get morning light. The NHS advises getting as much natural daylight as you can in winter. A walk before work counts.
- Think about vitamin D. From October to early March we don’t make enough from sunlight, so the NHS suggests a daily 10 microgram supplement. See vitamin D in winter.
- Watch for a pattern. If you feel low, sleep more and lose interest in things every winter, read about seasonal affective disorder (SAD).
More detail in how to protect your sleep when the clocks go back and why am I so tired in winter?
Nutrients that help with tiredness
Six vitamins and minerals have the same authorised health claim in Great Britain: magnesium, iron, vitamin B12, vitamin C, vitamin B6 and folate each contribute to a reduction of tiredness and fatigue. That only makes a difference if you’re not getting enough of them, so a balanced diet comes first.
| Nutrient | Good food sources | Who may run low |
|---|---|---|
| Magnesium | Wholegrains, nuts, seeds, green leafy vegetables, beans | Diets low in wholefoods; see signs of low magnesium |
| Iron | Red meat, beans, lentils, dark greens, fortified cereals | Heavy periods, pregnancy, little or no meat |
| Vitamin B12 | Meat, fish, eggs, dairy; fortified foods or a supplement if you’re vegan | Vegans and people who eat few animal foods |
| Vitamin B6 and folate | Poultry, fish, wholegrains, green vegetables, chickpeas | Restricted diets; see B vitamins and tiredness |
| Vitamin C | Citrus fruit, peppers, berries, broccoli | Few fruit and vegetables |
Vitamin D doesn’t have a tiredness claim, but most of us in the UK need it from October to early March: the NHS suggests 10 micrograms a day and no more than 100 micrograms a day.
Don’t take iron supplements unless a blood test shows you need them, as too much is harmful. With magnesium, the NHS says 400mg or less a day from supplements is unlikely to cause harm.
Our Magnesium Glycinate Sleep Complex is an evening drink with magnesium bisglycinate and citrate (148mg of magnesium per serving), glycine, L-theanine and botanicals. Magnesium contributes to a reduction of tiredness and fatigue. Our Reishi Mushroom Adaptogenic Complex is a reishi hot chocolate some people swap for a second coffee; it contains a little natural caffeine from the cacao, and reishi has no authorised health claims. Both are for adults only. We don’t recommend our products during pregnancy or breastfeeding, and if you take any medication, check with your GP or pharmacist first.
More on magnesium specifically: magnesium for energy. For a wider look, see best supplements for energy and how to boost energy naturally.
The FSA’s 10mg a day figure for CBD is precautionary advice rather than a legal limit, set while longer-term safety research continues. At Evopure we think it is a very cautious figure, and many adults use more. If you go above it, increase slowly, and check with your GP or pharmacist first if you take any medication.
When to see your GP
The NHS advises seeing a GP if you’ve felt tired for a few weeks and don’t know why, if tiredness is affecting your daily life, if you have other symptoms such as weight loss or mood changes, or if you’ve been told you gasp, snort or choke in your sleep. Keep a two-week diary of your sleep, energy, food and mood to take along.
Tired all the time blood tests
Your GP will usually start with blood tests to look for anaemia, thyroid problems, diabetes and inflammation. A Scottish audit of nearly 17,000 GP blood test requests for tiredness found a full blood count, kidney and liver tests and a thyroid test were each requested in at least 8 in 10 cases. Ferritin (your iron stores) was checked in fewer than 1 in 10 requests, but about 1 in 4 of those results was abnormal, so it’s reasonable to ask whether iron stores are included.
If your results come back normal, that’s useful information too: it points back to sleep, stress, mood and routine, which the plan above tackles.
Related guides
- Not getting enough sleep? See sleep deprivation: symptoms and how to recover.
- If you sleep a lot and are still tired, see why you might be oversleeping.
- Vitamin D deficiency symptoms.
- The best iron-rich foods, including vegetarian sources.
- If your GP prescribes iron, see iron tablets: how to take them and side effects.
- Thinking of trying B12? Read vitamin B12 supplements first, as they can hide a deficiency on a blood test.
- Tired and achy too? See body aches and tiredness.
- Is adrenal fatigue real?
- Tiredness is a common side effect of some weight-loss medicines; see Mounjaro tiredness and sleep.
- Feeling drained is often one of several stress symptoms, alongside poor sleep and headaches.
- Tiredness that started with a virus can linger; read how long a cold or flu lasts and when to see a GP.
FAQs
Why am I tired all the time even with enough sleep?
Poor-quality sleep, sleep apnoea, stress, low mood, anaemia, thyroid problems, diabetes or low activity can all leave you tired despite long nights. See a GP if it lasts a few weeks without a clear reason.
What deficiency makes you tired all the time?
Iron deficiency anaemia is the most common. Low vitamin B12, folate or vitamin D can also cause tiredness. A GP can check with a blood test.
Why do I feel light-headed and tired?
Dehydration, low blood pressure, anaemia, anxiety and, in people with diabetes, low blood sugar are common causes. Drink water, stand up slowly and see a GP if it keeps happening or you faint.
Why am I always cold and tired?
An underactive thyroid and anaemia are the two causes to rule out first. Not eating enough can also play a part. A GP can check thyroid and iron levels with a blood test.
What blood tests check for tiredness?
Usually a full blood count, kidney and liver function, a thyroid test, blood sugar and inflammation markers. Ferritin (iron stores) and vitamin levels may be added depending on your symptoms.
Does magnesium help with tiredness?
Magnesium contributes to a reduction of tiredness and fatigue, which helps if you’re not getting enough from food.
When should I worry about being tired all the time?
See a GP if you’ve been tired for a few weeks without a clear reason, it affects daily life, or you have other symptoms like weight loss or breathlessness.
How much sleep do adults need?
The NHS suggests aiming for 6 to 9 hours. Most adults feel best on around 7 to 9.
Sources
- NHS. Tiredness and fatigue.
- NHS. Self-help tips to fight tiredness.
- NHS. Iron deficiency anaemia.
- NHS. Underactive thyroid (hypothyroidism).
- NHS. Dizziness.
- NHS. Low blood pressure (hypotension).
- NHS. Dehydration.
- NHS. Low blood sugar (hypoglycaemia).
- NHS. Dry eyes.
- NHS. Sleep apnoea.
- NHS. Seasonal affective disorder (SAD).
- NHS. Vitamin D.
- NHS. Vitamins and minerals: others (magnesium).
- GOV.UK. Great Britain nutrition and health claims (NHC) register.
- GOV.UK. When do the clocks change?
- Handjiev S, Nobes J, Murphy MJ. ‘Tired all the time’: what general practitioners request and find in patients with tiredness/fatigue. Ann Clin Biochem, 2025. PMID 40085492.
- Ridsdale L et al. Patients who consult with tiredness: frequency of consultation, perceived causes of tiredness and its association with psychological distress. Br J Gen Pract, 1994. PMID 8790655.
- Harrison Y. The impact of daylight saving time on sleep and related behaviours. Sleep Med Rev, 2013. PMID 23477947.
This guide is general information, not medical advice. Evopure makes the Magnesium Glycinate Sleep Complex and Reishi Mushroom Adaptogenic Complex.
