Sleeping enough but
still tired all day?
Here’s what to check.
Tired all the time, even after a full night’s sleep? You’re not alone — tiredness is one of the most common reasons people see a doctor. Often the cause is something simple and fixable, like low iron, low vitamin B12 or low vitamin D — all very common in India. Here’s what doctors check, what each nutrient does for your energy, and what you can do.
If your tiredness is severe, lasts more than a few weeks, or comes with weight loss, fever, breathlessness or low mood, please see a doctor.
Tired all the time? Start with the common causes
Feeling tired all the time usually has a simple cause. Poor sleep, stress, anaemia, low B12 or vitamin D, thyroid problems and high blood sugar top the list. Most of these show up on a blood test and are easy to fix.
Tiredness isn’t an illness — it’s a sign that something needs attention. Think of the working mother who sleeps seven hours and still drags through the afternoon. Or the vegetarian student who feels flat for months, or the 45-year-old whose energy has quietly faded. Their tiredness feels the same, but the cause can be very different.
Everyday causes
- Not enough sleep, or poor-quality sleep
- Stress, worry or low mood
- Too little movement, or too much
- Skipped meals and too much sugar
- Recovering from an illness
Blood test for fatigue: what doctors check
For ongoing tiredness, doctors usually start with a blood count, iron stores (ferritin), thyroid, blood sugar, and liver and kidney tests. In India, vitamin B12 and vitamin D are worth adding, because so many people run low.
A good blood test for fatigue starts with the basics. UK health guidance lists a full blood count (to check for anaemia), thyroid function, blood sugar (HbA1c), liver and kidney tests and a test for coeliac disease, with ferritin (your iron stores) commonly added.6 B12, folate and vitamin D are added depending on your risk.6
In India, the risk is high for most people: about half of adults are low in B12 and most are low in vitamin D. So if you’re getting tested, ask for B12 and vitamin D too.
Iron and anaemia: the most common fixable cause
Iron carries oxygen in your blood. When iron runs low, you feel tired, weak and breathless. 57% of Indian women are anaemic. Even without anaemia, low iron stores can cause tiredness — and taking iron cut tiredness by almost half in one trial.
Iron helps your red blood cells carry oxygen around your body. When iron runs low, your muscles and brain get less oxygen — and you feel it as tiredness, weakness and breathlessness on the stairs. In India, 57% of women aged 15–49 are anaemic, against 25% of men.1
Low iron can make you tired even before you become anaemic. In a trial of women with unexplained tiredness and low iron stores but normal blood counts, iron tablets for 12 weeks cut tiredness by 48%, compared with 29% on a dummy pill.7 A review of several trials found the same.8 That’s why a ferritin test is worth asking for — especially for women.
Vitamin deficiency fatigue: B12 and the B vitamins
Your body needs B vitamins to turn food into energy. Vitamin B12 also makes healthy red blood cells. About half of Indian adults are low in B12, especially vegetarians and people on metformin. B vitamins contribute to normal energy and help reduce tiredness.
Think of food as fuel and B vitamins as the spark plugs. Vitamins B2, B3, B5, B6 and B12 each help your cells turn food into energy you can use.9 When one runs low, that process slows down — and you feel tired.
Vitamin B12 matters most. It helps make healthy red blood cells and keeps your nerves working. In a North Indian study, 47% of adults were low in B12.2 It comes mainly from milk, eggs, fish and meat, so vegetarians are most at risk — and so are people taking metformin for diabetes.10 Read our vitamin B12 guide for more.
Vitamin D: low in most Indians
Vitamin D keeps your muscles and bones working well. Studies find 70–100% of people in India are low in it, even with all our sunshine. Low vitamin D is linked with tiredness, muscle weakness and aches.
India has plenty of sunshine, yet 70–100% of people in Indian studies are low in vitamin D.3 Indoor jobs, pollution and covered clothing mean most of us get too little sun on our skin. Very low vitamin D can cause muscle weakness, aches and tiredness.11 A simple 25(OH)D blood test shows your level.
Magnesium: the one blood tests often miss
Magnesium helps your body make energy in every cell and contributes to reducing tiredness. But the usual blood test only sees about 1% of your body’s magnesium, so low levels are easy to miss.
Magnesium helps power more than 300 jobs in your body, including making energy inside every cell. It contributes to normal energy and reducing tiredness.9 The catch: the usual blood test measures only the magnesium in your blood — about 1% of what your body holds. The rest is in your bones and cells.12 So a “normal” result doesn’t always mean you have enough.
Magnesium also helps with stress, which often comes with tiredness. In adults with stress and low magnesium, 300 mg of magnesium a day reduced stress, and adding vitamin B6 helped even more in those with severe stress.13 Read our magnesium deficiency guide.
“Most tiredness has a cause you can find with a blood test. In India, iron, B12 and vitamin D are the first places to look.”
The simple version
Your tiredness lasts more than a few weeks, stops you doing everyday things, or comes with weight loss, fever, night sweats, breathlessness, swelling or low mood. These need a proper check-up.
Vitamins for energy, in forms your body can use.
Two products that keep the everyday energy nutrients topped up. Our multivitamin is iron-free on purpose — so iron can be decided by a blood test.
Bioactive Multivitamin
Active B vitamins — benfotiamine B1, riboflavin-5-phosphate B2, niacinamide B3, B5, P5P B6 and methylcobalamin B12 — plus vegan vitamin D3. Vitamins B2, B3, B5, B6 and B12 contribute to normal energy-yielding metabolism and the reduction of tiredness and fatigue. Iron-free by design: if a test shows you’re low in iron, your doctor can give you the right dose.
See the multivitamin →Element 5
300 mg of magnesium from gentle bisglycinate, Aquamin® marine magnesium and taurate, with P5P vitamin B6 — the magnesium-and-B6 pairing studied for stress. Magnesium contributes to the reduction of tiredness and fatigue. It’s a separate product because 300 mg of magnesium needs room of its own.
See Element 5 →What to do if you’re tired all the time
See a doctor for warning signs. Fix sleep first. Get a blood test with a blood count, ferritin, thyroid, sugar, B12 and vitamin D. Treat what you find, and keep your everyday nutrients topped up.
- See a doctor for warning signsWeight loss, fever, night sweats, breathlessness, swelling, low mood, or tiredness lasting weeks all need a check-up.
- Fix sleep firstAim for seven to nine hours, keep a regular bedtime, and cut screens and caffeine late in the day.
- Get the right blood testsAsk for a blood count, ferritin, thyroid, HbA1c, vitamin B12 and vitamin D.
- Treat what you findLow iron, B12 or vitamin D often need a stronger dose from your doctor first.
- Keep your levels steadyA daily multivitamin and magnesium help keep your everyday energy nutrients topped up.
- The iron trial included menstruating women with unexplained tiredness, ferritin below 50 µg/L and normal haemoglobin. They took 80 mg of iron a day for 12 weeks.7 A trial of iron given by drip to blood donors did not reduce tiredness.14
- The magnesium stress trial used 300 mg of magnesium a day for eight weeks in adults with low magnesium. The vitamin B6 used alongside was 30 mg (as pyridoxine).13
- The B12 figure comes from a study in North India; vitamin D figures come from a review of Indian studies.2,3
- The blood-test list follows UK primary-care guidance; your doctor may add or skip tests based on your symptoms.6
Tiredness, answered simply.
Why am I tired all the time even after sleeping well?
Which blood test should I get for fatigue?
Which vitamin deficiency causes tiredness?
Can low iron make me tired without anaemia?
Does B12 deficiency cause fatigue?
Can low vitamin D make you tired?
Does magnesium help with tiredness?
What are the best vitamins for energy?
Why is the Evo Hominus™ multivitamin iron-free?
When should I see a doctor about tiredness?
Studies behind this guide
- Ministry of Health and Family Welfare, IIPS. National Family Health Survey (NFHS-5), 2019–21 — anaemia in 57.0% of women and 25.0% of men aged 15–49.
- Singla R, Garg A, Surana V, et al. Vitamin B12 deficiency is endemic in Indian population: a perspective from North India. Indian J Endocrinol Metab. 2019;23(2):211–4. PMID 31161105
- Ritu G, Gupta A. Vitamin D deficiency in India: prevalence, causalities and interventions. Nutrients. 2014;6(2):729–75. PMID 24566435
- Unnikrishnan AG, Kalra S, Sahay RK, et al. Prevalence of hypothyroidism in adults: an epidemiological study in eight cities of India. Indian J Endocrinol Metab. 2013;17(4):647–52.
- Anjana RM, Unnikrishnan R, Deepa M, et al. Metabolic non-communicable disease health report of India: the ICMR-INDIAB national cross-sectional study (ICMR-INDIAB-17). Lancet Diabetes Endocrinol. 2023;11(7):474–89 — prediabetes 15.3%.
- National Institute for Health and Care Excellence. Clinical Knowledge Summaries: Tiredness/fatigue in adults — first-line investigations.
- Vaucher P, Druais PL, Waldvogel S, Favrat B. Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. CMAJ. 2012;184(11):1247–54. DOI 10.1503/cmaj.110950 — n=198.
- Iron deficiency without anaemia is a potential cause of fatigue: meta-analyses of randomised controlled trials and cross-sectional studies. Br J Nutr. 2017.
- Commission Regulation (EU) No 432/2012 — authorised health claims: vitamins B2, B3, B5, B6, B12 and magnesium contribute to normal energy-yielding metabolism and to the reduction of tiredness and fatigue.
- Niafar M, Hai F, Porhomayon J, Nader ND. The role of metformin on vitamin B12 deficiency: a meta-analysis review. Intern Emerg Med. 2015;10(1):93–102. PMID 25502588
- NIH Office of Dietary Supplements. Vitamin D — Fact Sheet for Health Professionals.
- NIH Office of Dietary Supplements. Magnesium — Fact Sheet for Health Professionals (under 1% of body magnesium is in blood serum).
- Pouteau E, Kabir-Ahmadi M, Noah L, et al. Superiority of magnesium and vitamin B6 over magnesium alone on severe stress in healthy adults with low magnesemia: a randomized, single-blind clinical trial. PLoS One. 2018;13(12):e0208454.
- Keller P, von Känel R, Hincapié CA, et al. The effects of intravenous iron supplementation on fatigue and general health in non-anemic blood donors with iron deficiency: a randomized placebo-controlled superiority trial. Sci Rep. 2020;10:14219.