Constantly feeling tired, with everyone just telling you "it's only stress"?
Constantly feeling tired, with everyone just telling you "it's only stress"?
It is easy to assume that feeling exhausted is simply down to stress. However, in many cases, there is an underlying physical cause that we can easily spot with a simple blood test.
It is easy to assume that feeling exhausted is simply down to stress. However, in many cases, there is an underlying physical cause that we can easily spot with a simple blood test.
PVZ Editorial Team · 21 July 2026 · 3 min read
PVZ Editorial Team · 21 July 2026 · 3 min read
After moving to Vienna, Sophie felt exhausted for months. Climbing stairs became a struggle, her concentration slipped, and in the mornings, she felt as if she hadn't slept at all. The explanation seemed obvious: a new city, a new job, plenty of stress.
And that is precisely the most common misconception when it comes to persistent tiredness. Stress is a plausible explanation, but it is also an easy one. If you are constantly tired, there is a physical cause in a significant number of cases that can be easily identified with just a few laboratory values and treated.
When tiredness goes beyond normal exhaustion
It is perfectly normal to feel tired after a short night's sleep. However, you should have your tiredness medically investigated if it falls into any of these patterns:
It has lasted for more than four weeks.
It doesn't improve even after plenty of sleep and a relaxing weekend off.
Your physical resilience has noticeably decreased, for example during sport or when climbing the stairs.
Other symptoms are also cropping up, such as changes in weight, hair loss, shortness of breath, feeling cold, heart palpitations, or low mood.
The most common physical causes
Iron deficiency. By far the most common cause, especially in menstruating women. Typical signs include paleness, exhaustion, reduced performance, feeling cold, and being more prone to infections. [1] Crucially, an iron deficiency can exist before it shows up in your blood count. That is why your ferritin levels should always be checked too.
Underactive thyroid (hypothyroidism). If your thyroid gland produces too little hormone, many of your body's functions slow down. Tiredness, a slow pulse, dry skin, constipation, and weight gain are classic signs. [2] A single TSH level test is enough for an initial assessment.
Sleep apnoea. If your breathing repeatedly pauses during the night, you might sleep for a long time, but it won't be restful. Pronounced daytime tiredness is the main symptom here. [3] Loud snoring and witnessed pauses in breathing are clear warning signs.
Other common causes include vitamin B12 deficiency, previously undetected type 2 diabetes, chronic inflammation, side effects from medication, and depressive disorders. Alcohol is also an underestimated factor because it reliably disrupts your deep sleep.
What we investigate in cases of persistent tiredness
The very first step is not a test, but a friendly chat. How long have you felt tired, what is your sleep like, what medications are you taking, and have you noticed any changes in your weight? This discussion helps us figure out which tests will actually be helpful for you.
In most cases, a targeted lab test brings real clarity: blood count, ferritin, TSH, blood sugar, inflammation markers, liver and kidney values, and vitamin B12 if suspected. This is accompanied by a blood pressure reading and a physical examination. This investigation is part of general medical care and is free of charge for NHS patients.
What happened next for Sophie
Sophie finally decided to book an appointment instead of googling her symptoms. After a chat and a lab test, the cause was found, and the treatment was very straightforward. Six months later, she describes her energy levels as even better than before her house move. For her, the real win wasn't just the therapy, but finally putting an end to the uncertainty.
When tiredness goes beyond normal exhaustion
It is perfectly normal to feel tired after a short night's sleep. However, you should have your tiredness medically investigated if it falls into any of these patterns:
It has lasted for more than four weeks.
It doesn't improve even after plenty of sleep and a relaxing weekend off.
Your physical resilience has noticeably decreased, for example during sport or when climbing the stairs.
Other symptoms are also cropping up, such as changes in weight, hair loss, shortness of breath, feeling cold, heart palpitations, or low mood.
The most common physical causes
Iron deficiency. By far the most common cause, especially in menstruating women. Typical signs include paleness, exhaustion, reduced performance, feeling cold, and being more prone to infections. [1] Crucially, an iron deficiency can exist before it shows up in your blood count. That is why your ferritin levels should always be checked too.
Underactive thyroid (hypothyroidism). If your thyroid gland produces too little hormone, many of your body's functions slow down. Tiredness, a slow pulse, dry skin, constipation, and weight gain are classic signs. [2] A single TSH level test is enough for an initial assessment.
Sleep apnoea. If your breathing repeatedly pauses during the night, you might sleep for a long time, but it won't be restful. Pronounced daytime tiredness is the main symptom here. [3] Loud snoring and witnessed pauses in breathing are clear warning signs.
Other common causes include vitamin B12 deficiency, previously undetected type 2 diabetes, chronic inflammation, side effects from medication, and depressive disorders. Alcohol is also an underestimated factor because it reliably disrupts your deep sleep.
What we investigate in cases of persistent tiredness
The very first step is not a test, but a friendly chat. How long have you felt tired, what is your sleep like, what medications are you taking, and have you noticed any changes in your weight? This discussion helps us figure out which tests will actually be helpful for you.
In most cases, a targeted lab test brings real clarity: blood count, ferritin, TSH, blood sugar, inflammation markers, liver and kidney values, and vitamin B12 if suspected. This is accompanied by a blood pressure reading and a physical examination. This investigation is part of general medical care and is free of charge for NHS patients.
What happened next for Sophie
Sophie finally decided to book an appointment instead of googling her symptoms. After a chat and a lab test, the cause was found, and the treatment was very straightforward. Six months later, she describes her energy levels as even better than before her house move. For her, the real win wasn't just the therapy, but finally putting an end to the uncertainty.
"I thought I just needed to pull myself together. But actually, there was a reason for it that could be measured."
"I thought I just needed to pull myself together. But actually, there was a reason for it that could be measured."
"I thought I just needed to pull myself together. But actually, there was a reason for it that could be measured."
Practical Advice
If your tiredness lasts for more than a month, it is a great idea to get it checked out before you start doubting your self-discipline! A simple blood test takes just five minutes and is a wonderful, reliable way to either rule out or find the most common causes.
At the PVZ Primärversorgungszentrum in Vienna's Josefstadt, we are happy to look into this for you as part of your general medical care or during your next preventative health check. You can easily book your appointment at Appointments and Contact.
Frequently Asked Questions
When does constant tiredness become a matter for a doctor?
If your tiredness has lasted for more than four weeks, does not improve with sleep, or is noticeably affecting your daily performance, it is time to get in touch. Please do not wait to seek advice if you also notice weight changes, shortness of breath, or heart palpitations.
Which blood levels are tested for tiredness?
Typically, we will check your full blood count, ferritin (to measure your iron stores), TSH for thyroid function, blood sugar, inflammatory markers, as well as liver and kidney function. Depending on your medical history, we might also check your vitamin B12 levels.
Can iron deficiency cause tiredness even if my blood count is normal?
Yes, absolutely! Your body's iron stores can already be depleted before your haemoglobin levels start to change. That is why we always check your ferritin levels as well.
Is tiredness a sign of depression?
It certainly can be. Persistent exhaustion is a very common symptom of depressive illnesses. That is why a thorough assessment always looks at both sides of the coin: a physical check-up alongside a supportive conversation.
Will iron or vitamin supplements from the chemist help?
Only if you actually have a deficiency! Taking iron supplements just in case is not harmless and can cause unpleasant side effects. We highly recommend getting your levels checked before you start supplementing.
Sources
Austrian Health Portal. Iron Deficiency and Iron Deficiency Anaemia. Link
Austrian Health Portal. Thyroid: Function and Diseases. Link
Austrian Health Portal. Obstructive Sleep Apnea. Link
This article is for general informational purposes only and does not replace individual medical advice.
Practical Advice
If your tiredness lasts for more than a month, it is a great idea to get it checked out before you start doubting your self-discipline! A simple blood test takes just five minutes and is a wonderful, reliable way to either rule out or find the most common causes.
At the PVZ Primärversorgungszentrum in Vienna's Josefstadt, we are happy to look into this for you as part of your general medical care or during your next preventative health check. You can easily book your appointment at Appointments and Contact.
Frequently Asked Questions
When does constant tiredness become a matter for a doctor?
If your tiredness has lasted for more than four weeks, does not improve with sleep, or is noticeably affecting your daily performance, it is time to get in touch. Please do not wait to seek advice if you also notice weight changes, shortness of breath, or heart palpitations.
Which blood levels are tested for tiredness?
Typically, we will check your full blood count, ferritin (to measure your iron stores), TSH for thyroid function, blood sugar, inflammatory markers, as well as liver and kidney function. Depending on your medical history, we might also check your vitamin B12 levels.
Can iron deficiency cause tiredness even if my blood count is normal?
Yes, absolutely! Your body's iron stores can already be depleted before your haemoglobin levels start to change. That is why we always check your ferritin levels as well.
Is tiredness a sign of depression?
It certainly can be. Persistent exhaustion is a very common symptom of depressive illnesses. That is why a thorough assessment always looks at both sides of the coin: a physical check-up alongside a supportive conversation.
Will iron or vitamin supplements from the chemist help?
Only if you actually have a deficiency! Taking iron supplements just in case is not harmless and can cause unpleasant side effects. We highly recommend getting your levels checked before you start supplementing.
Sources
Austrian Health Portal. Iron Deficiency and Iron Deficiency Anaemia. Link
Austrian Health Portal. Thyroid: Function and Diseases. Link
Austrian Health Portal. Obstructive Sleep Apnea. Link
This article is for general informational purposes only and does not replace individual medical advice.
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