Why Am I Always Tired? Medical Causes Worth Checking

Written by AT. Chintan Dalal, N.D. · Reviewed by Dr Krushal Pabari, Clinical Team, Cure4Pain · Updated 30 October 2026

Key facts

If you are always tired, the likeliest explanations are sleep problems, depression and long-term stress, according to a 2021 review based on the German general practice guideline on fatigue [1]. A 2016 review of 26 primary care studies found depression in 18.5% of people who saw a doctor about tiredness, serious physical disease in 4.3%, anaemia in 2.8% and cancer in 0.6% [2]. In a Dutch study of 571 adults with new tiredness in general practice, about half had no diagnosis that could explain it within a year [3]. The UK’s NHS advises seeing a doctor if you have been tired for a few weeks without knowing why, if it affects your daily life, or if you also have symptoms such as weight loss or mood changes [4].

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Why am I always tired?

The most common explanations for constant tiredness are sleep problems, depression and long-term stress, according to a 2021 review based on the German general practice guideline [1], and daily habits or a medical condition can also play a part. The NHS lists too little sleep or insomnia, poor diet and little exercise, stress, depression, life events such as bereavement or a new baby, hormonal changes in pregnancy or the menopause, illnesses such as glandular fever and COVID-19, and some medicines [4]. Among serious physical diseases, diabetes, anaemia and hypothyroidism (an underactive thyroid) were the most frequent in a 2016 systematic review of 26 primary care studies [2], and low iron or vitamin B12 can be present without anaemia [5] [6].

Tiredness and sleepiness differ. According to a 2023 review in American Family Physician, sleepiness is the tendency to doze off and responds to rest, while fatigue may or may not respond to rest [7]. Tell your doctor which one you have.

Which medical causes of constant tiredness are most common?

Depression was the most frequent cause that a 2016 systematic review of 26 primary care studies could combine across its high-quality studies: 18.5% of people who saw a doctor about tiredness, against 4.3% for serious physical disease [2]. These figures come from people who saw a family doctor about tiredness, not from hospital patients. The Dutch figures below come from 571 adults with new tiredness, followed for a year in 147 general practices [3].

Cause	What primary care studies found	Clues to mention
Depression	18.5% in a review of 26 studies [2]	Low mood, no interest in things, disturbed sleep [8]
Sleep problems	Reported by 65.0% in a Dutch study but recorded in 1.9% of charts [3]	Snoring, pauses in breathing seen by others, not feeling rested [1] [7]
Stress and burnout	55.7% in a Dutch study put their tiredness down to stress or worry; strain or burnout recorded in 31 of 571 [3]	Long-term difficulties at work, at home or with money [3]
Infections	Respiratory infections were among the strongest links in an English study of 304,914 people [9]	A recent illness [4]; a cough lasting over 3 weeks, as in tuberculosis [10]
Anaemia	2.8% in a review of 26 studies [2]	Heavy or frequent periods [11] [9]
Thyroid disease	Hypothyroidism in 7 and an overactive thyroid in 3 of 571 in a Dutch study [3]	Feeling cold, weight gain, constipation, dry skin [12]
Diabetes	4 of 571 in a Dutch study [3]	Thirst, passing more urine, weight loss [13]
Medicines	Adverse effects in 6 of 571 in a Dutch study [3]	Antihistamines, benzodiazepines, antidepressants, blood pressure medicines, opiates; alcohol [1]
Cancer	0.6% in a review of 26 studies [2]	Weight loss, a new lump, night sweats, unusual bleeding [14]
ME/CFS (chronic fatigue syndrome)	4 of 571 in a Dutch study [3]	Worse after activity, not relieved by rest [15]

Two cautions apply to these figures. First, 12 of the 26 studies in the 2016 review, the largest group, were done in Europe, and in PubMed searches on 30 October 2026 we found no primary care study of tiredness from India. Some causes may be more common in India: anaemia in 57% of non-pregnant women aged 15 to 49 in the National Family Health Survey 2019-21 [11], hypothyroidism in 10.95% of adults in eight Indian cities, with 3.47% previously undetected [16], and diabetes in 11.4% of adults in the ICMR-INDIAB survey [17]; these surveys did not study people with tiredness.

Second, a finding is not always the reason for tiredness: in the 2016 review, studies with a comparison group found physical disease as common in people without tiredness, so the authors say the link may not be causal, although depression was more frequent in people with tiredness [2].

Can depression make you always tired?

Yes, depression can make you always tired. The NHS lists lack of energy and disturbed sleep among the physical symptoms of depression [8], and in a Dutch general practice study of adults with new tiredness, 24.1% reported depressive symptoms while 4.9% had them recorded [3]. The tiredness of depression is real, and treatments include talking therapies and medicines [1].

• Two useful questions: how often in the past 2 weeks have you felt low in mood, and had little interest in doing things? These form the PHQ-2 screening tool. In a 2003 study, 6,000 primary care and obstetrics-gynaecology patients completed it and 580 were also interviewed by a mental health professional; against that interview, a score of 3 or more had 83% sensitivity and 92% specificity for major depression [18]. The PHQ-2 does not make a diagnosis.
• When to see a doctor: the NHS advises this if you have symptoms for most of the day, every day, for more than 2 weeks [8].
• Thoughts of harming yourself: these need urgent help. If you may be about to act on them, the NHS advises emergency care [19]; call your local emergency number or go to the nearest emergency department.

Why am I always tired even after sleeping?

Waking tired after enough hours of sleep can point to poor sleep quality, and sleep apnoea is one cause to check. In a 2000 study of 190 people with obstructive sleep apnoea at a US sleep laboratory, more reported lack of energy (62%), tiredness (61%) and fatigue (57%) than sleepiness (47%) [20], so feeling tired rather than sleepy does not rule out sleep apnoea.

Tell your doctor about snoring, pauses in breathing that someone has seen, or falling asleep at the wheel [1]. Our article on waking up tired with snoring or sleep apnoea covers screening questionnaires and sleep studies. Our snoring page covers snoring and mouth breathing, and our insomnia page covers trouble falling or staying asleep. The NHS suggests aiming for 6 to 9 hours, with no food, caffeine or exercise in the couple of hours before sleep and no screens in the last hour [4].

Which deficiencies and blood tests are worth checking?

For constant tiredness, the German general practice guideline, as described in a 2021 review, lists fasting blood sugar, a complete blood count, ESR or CRP (inflammation tests), liver enzymes and TSH (a thyroid test), with ferritin for premenopausal women whose assessment is otherwise normal [1]. This short set is a reasonable start, with more only if your history points to something; iron and vitamin B12 are two deficiencies to ask about. Our article on blood tests for chronic pain and fatigue covers the longer NICE list and a Dutch trial in which wider test sets gave more false positives [21].

• Iron: in a 2018 systematic review of 18 trials in iron-deficient adults without anaemia, iron reduced self-reported fatigue but did not improve measured physical capacity [5]. See iron deficiency without anaemia.
• Vitamin B12: NICE NG239 (2024) lists unexplained fatigue among common symptoms and says a deficiency should not be ruled out only because anaemia is absent [6]. See vitamin B12 deficiency.
• Thyroid: an underactive thyroid can cause extreme tiredness, according to the NHS [12]; see our hypothyroidism page. A mild result is different: in the TRUST trial of 737 adults aged 65 and over with subclinical hypothyroidism (raised TSH, normal thyroid hormone), levothyroxine did not change tiredness scores at 1 year compared with placebo [22].

Could it be chronic fatigue syndrome or fibromyalgia?

Long-lasting tiredness can be chronic fatigue syndrome (ME/CFS) or fibromyalgia, but most people with long-lasting tiredness do not have chronic fatigue syndrome, according to a 2023 review in American Family Physician [7]. Neither ME/CFS nor fibromyalgia has a confirming blood test [15] [23].

• ME/CFS: NICE NG206 (2021) advises suspecting it when, for at least 6 weeks in adults and with no other explanation, a person has all of these and can do much less than before: debilitating fatigue worsened by activity and not significantly relieved by rest; worsening after activity, often hours or days later; unrefreshing or disturbed sleep; and difficulties with thinking. ME/CFS is diagnosed once these symptoms have persisted for 3 months. NICE advises against graded exercise therapy with fixed increases [15], so mention any worsening after activity before starting an exercise plan.
• Fibromyalgia: the 2012 Canadian guideline describes fluctuating, diffuse body pain with frequent sleep disturbance, fatigue, and changes in mood and thinking [23]. See our fibromyalgia page.

When is tiredness a warning sign?

Tiredness alone is rarely an emergency, but crushing or squeezing chest pain, severe difficulty breathing or thoughts that you may harm yourself need emergency help, and unexplained weight loss, a new lump, constant thirst, a cough lasting over 3 weeks or falling asleep while driving need a doctor soon.

Get emergency help for:

• Chest pain that feels crushing or squeezing [24], or severe difficulty breathing [25].
• Thoughts that you may harm yourself [19].

See a doctor soon for:

• Losing weight without trying, a new lump, unusual bruising or bleeding, or night sweats or a high temperature that keeps coming back [14].
• Being thirsty all the time and passing more urine [13].
• A cough lasting more than 3 weeks [10].
• Gasping or choking in your sleep [4], or falling asleep while driving [1].
• New tiredness in older age: in a 2022 study of 250,606 adults in England, the 12-month cancer risk after a first visit for tiredness was above 3% in men aged 65 and over and women aged 80 and over [26]. A 2024 English study of 304,914 people supports prioritising cancer checks in men aged 70 and over, but not in women on the basis of tiredness alone [9].

What if no cause is found?

Finding no cause for tiredness is common and does not mean the tiredness is not real: about half of 571 adults with new tiredness in a Dutch general practice study had no diagnosis that could explain it within a year [3], and one half to two thirds of patients with tiredness were still tired after a year in a 1992 study from two Canadian family medicine clinics [27].

A 2021 review based on the German general practice guideline advises follow-up every 4 to 6 weeks rather than ever wider testing, and discussing behaviour therapy and an activity programme suited to you [1]. It helps to tell your doctor how long you have been tired, what makes it better or worse, how you feel after activity, and whether you wake rested [7].

How we look at constant tiredness at Cure4Pain

At Cure4Pain, we look for what is disturbing your sleep, energy and thyroid function, and work alongside your existing consulting physician.

• Tests: we read a panel of about 100 markers, including vitamin D, B12, iron, thyroid, blood sugar, cortisol and ANA, adding tests for your condition when clinically indicated, such as creatine kinase and coeliac screening from NICE NG206 (2021) [15], and a sleep study when sleep apnoea is suspected. This is our clinic practice and is wider than the guideline lists. In the Dutch trial of new unexplained fatigue, false-positive results rose with wider test sets; that trial randomised when tests were ordered, not how many [21]. We found no trial randomising people with long-lasting tiredness to a broad panel or a shorter list.
• Sleep and daily habits: we advise limiting caffeine, alcohol and excess sugar, with no late-night dinners, a sleep routine, morning light, fewer screens, and cognitive behavioural therapy for insomnia or relaxation methods.
• Food: as clinic practice, we generally advise most patients to replace wheat with jowar, bajra or other millets as a general health measure, including home-made roti from processed wheat; a gluten-free diet is supported for coeliac disease and positive tests, and the NHS says people with coeliac disease must stop all gluten for life [28]. Also, as an observational clinic practice, we generally suggest limiting cruciferous (Brassica) vegetables such as cabbage and cauliflower; a 2024 review found that eating them, particularly with enough iodine, had no adverse effect on thyroid function [29].
• Nutrients and vitamin D: a methylated B-vitamin complex and, at times, magnesium for sleep; selenium, zinc, iron, B12, magnesium and standard vitamin D doses for hypothyroidism. Supplements are given by mouth first, with injections only when specifically needed or advised; magnesium is mainly bisglycinate, with L-threonate or citrate as advised, counted as elemental magnesium, and absorption varies by form. Apart from the iron trials above [5], this article cites no trial of these nutrients for tiredness. For sleep problems, supervised-dose vitamin D therapy (Coimbra Protocol-based methods), monitored with blood tests. Our methods are derived from the work of Dr Coimbra. We found no controlled trial of this therapy in tiredness or insomnia.
• Thyroid care: counselling on weight, sleep, stress and exercise, with blood tests every 3 months. The TRUST trial found no effect of levothyroxine on tiredness in older adults [22]; for subclinical hypothyroidism we choose nutrition support, medicine or both for each person, by clinical need.
• Medicines: Dr Krushal Pabari manages thyroid medicine and reviews sleeping pills, under clinical guidance from Team Cure4Pain, in coordination with your existing consulting physician and the doctor who prescribed them; never stop or change them on your own. We work with psychiatrists and sleep specialists where needed.
• What we have observed: within 8 to 12 weeks, most people we see for sleep problems report better sleep quality, and many people with hypothyroidism who follow the plan report better energy and steadier thyroid results within about 12 to 18 weeks, most while continuing their thyroid medicine where it is needed. These are clinic observations, not trial results; individual results vary, and they do not cover tiredness from other causes.

This is our clinic practice; individual results vary, and further studies are needed.

If you would like your tiredness, sleep and test results looked at together, you can book a consultation, online from anywhere or at our Mumbai clinic.

Frequently asked questions

Why am I always tired and have no energy?

The most common explanations for constant tiredness and low energy are sleep problems, depression and long-term stress, according to a 2021 review based on the German general practice guideline. Anaemia, thyroid disease, diabetes and medicines are less common but worth checking. [1] [2]

Why am I always tired even after a full night’s sleep?

Poor sleep quality is one reason for waking tired after a full night’s sleep, and sleep apnoea is one cause to check. In a 2000 study of 190 people with sleep apnoea, more reported lack of energy (62%) than sleepiness (47%). [20]

What deficiency makes you tired all the time?

Iron and vitamin B12 are two deficiencies to check. In a 2018 review of 18 trials, iron reduced self-reported fatigue in iron-deficient adults without anaemia, and NICE lists unexplained fatigue among the common symptoms of low B12. [5] [6]

Is being tired all the time a sign of cancer?

Being tired all the time is rarely a sign of cancer on its own. Cancer was found in 0.6% of people in a review of 26 primary care studies. Risk rises with age, and a 2024 English study supports prioritising cancer checks in men aged 70 and over with tiredness. [2] [26] [9]

Why are women tired all the time?

In English women aged 40 who saw a doctor about tiredness, the conditions most linked with it included depression, heavy or frequent periods and upper respiratory infections, and at age 60 thyroid disease was also prominent, according to a 2024 study. The NHS also lists hormonal changes in pregnancy or the menopause among the causes of tiredness. [9] [4]

Can a thyroid problem make me always tired?

Yes, a thyroid problem can make you always tired: the NHS lists extreme tiredness as a symptom of an underactive thyroid. In adults aged 65 and over with subclinical hypothyroidism, though, levothyroxine did not change tiredness scores in the TRUST trial. [12] [22]

How do I know if it is chronic fatigue syndrome?

NICE guideline NG206 (2021) advises suspecting ME/CFS when, for at least 6 weeks in adults, there is debilitating fatigue worsened by activity, delayed worsening after activity, unrefreshing sleep and thinking difficulties, with no other explanation. ME/CFS is diagnosed once these symptoms have persisted for 3 months, and no test confirms it. [15]

When should I see a doctor about tiredness?

The NHS advises seeing a doctor if you have been tired for a few weeks without knowing why, if it affects your daily life, or if you also have symptoms such as weight loss or mood changes. [4]

This article is for education and does not replace medical advice. Do not start, stop or change any medicine or supplement without medical guidance.

References

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