Why Do I Feel Tired All the Time?
Understanding the biological causes of persistent fatigue
Feeling tired from time to time is part of life. But when tiredness becomes persistent — when sleep does not feel restorative, concentration becomes harder, and everyday tasks begin to feel heavier — it is often a sign that something deserves a closer look.
Fatigue can of course be influenced by stress, poor sleep, overwork or emotional strain. But it can also be linked to biological factors such as iron deficiency, low vitamin B12, low vitamin D, thyroid dysfunction or changes in blood sugar regulation. The NHS lists tiredness and lack of energy among the common symptoms of iron deficiency anaemia, vitamin B12 or folate deficiency, vitamin D deficiency and underactive thyroid function.
That matters because fatigue is a symptom, not a diagnosis. In other words, it tells you that something may be off balance, but not what that "something" actually is. A blood test can help provide that missing clarity by looking at the systems most commonly associated with low energy.
Biomarkers that may help provide answers
Several blood markers can be helpful when exploring persistent fatigue, including:
- Iron and ferritin
- Vitamin B12 and folate
- Vitamin D
- Thyroid markers such as TSH and free T4
- Glucose and HbA1c
HbA1c reflects average blood glucose over the last two to three months, which can be useful when considering metabolic contributors to tiredness.
The Cocoon perspective
At Cocoon, we believe feeling well should not be left to guesswork. If your energy feels lower than it should, blood testing can offer a calmer, more informed place to begin.
Our Tired All the Time test is designed to look at several of the most common biological drivers of fatigue, helping you understand what your body may be trying to tell you.