Quick answer: Feeling tired all the time is common, but it isn’t “just aging” or laziness. Persistent fatigue usually has identifiable contributors: low iron stores, thyroid under-function, disrupted cortisol rhythm, poor sleep, blood sugar swings, nutrient gaps, or hidden inflammation. The most effective approach is to test for these root causes, then support sleep, nutrition and cellular energy (mitochondria) based on what you find.
Key takeaways
Constant tiredness is common, but it usually has identifiable contributors rather than being just aging.
Low iron stores, an underactive thyroid, a disrupted cortisol rhythm, poor sleep and blood sugar swings are among the most frequent.
Testing for these contributors first allows support for sleep, nutrition and cellular energy to be matched to you.
What’s really behind constant fatigue?
Your cells make energy (ATP) in their mitochondria. When something interferes with that process, every system can slow down: brain fog sets in, muscles feel heavy, and mood and hormones suffer. Common contributors include:
- Low iron stores: low ferritin can contribute to fatigue even before anemia appears (see ferritin levels explained)
- Thyroid under-function: including poor conversion of T4 to active T3 (see TSH and thyroid health)
- Cortisol rhythm disruption: feeling “tired but wired,” or crashing mid-afternoon (see hidden cortisol patterns)
- Nutrient gaps: magnesium, B12, folate and vitamin D (see who should consider magnesium)
- Blood sugar swings, poor sleep, and hidden inflammation
Nutrients and botanicals studied for energy
These are commonly used to support cellular energy. Research quality varies, and doses should be individualized, so please discuss them with your provider before starting:
CoQ10 (ubiquinol) is part of the mitochondrial energy chain and can interact with blood thinners such as warfarin. D-ribose is a building block of ATP, and acetyl-L-carnitine and alpha-lipoic acid help move fats into mitochondria and support antioxidant defenses. Adaptogens (ashwagandha, rhodiola, holy basil) have been studied for stress resilience and fatigue.
Magnesium and active B vitamins are cofactors for energy-producing enzymes. Iron with vitamin C is used only when testing shows low iron stores, because too much iron can be harmful. PQQ and NADH have been studied for mitochondrial support.
If you work with me, you can find the products I use in my Fullscript dispensary.
Daily habits that support energy
Get 10–20 minutes of morning daylight, which helps set your cortisol and circadian rhythm, and try finishing dinner a few hours before bed. Take short movement breaks every 60–90 minutes to avoid energy crashes.
Keep a consistent sleep schedule, and ask about sleep apnea if you snore or wake unrefreshed. Brief cold exposure, such as a cool shower finish, is an option if you enjoy it and have no heart concerns.
Labs to consider for persistent fatigue
For persistent fatigue, labs to consider include a CBC, ferritin, transferrin saturation, vitamin D, B12 and RBC magnesium, along with a full thyroid panel, including free T3, reverse T3 and antibodies. A daily cortisol rhythm test (4-point or DUTCH) plus DHEA, organic acids (mitochondrial and Krebs cycle markers), and blood sugar markers (fasting glucose, insulin, HbA1c) can also be useful.
Low cellular energy is also tied to how we age. Learn more in revitalizing your mitochondria and the Longevity Protocol.
When to see a naturopathic doctor
It may be time to see a naturopathic doctor if fatigue lasts more than a few weeks despite good sleep, or if your labs were “normal” but you still feel drained. The same is true if fatigue comes together with brain fog, weight changes, hair loss, low mood or poor exercise recovery, or if you want a plan built on testing instead of trial and error.
Seek care promptly if fatigue comes with chest pain, shortness of breath, fainting, unexplained weight loss, fever or night sweats, or thoughts of self-harm.
Tired of being tired? Let’s find out what’s draining your energy.
A free 15-minute consultation with Dr. Kneessi. No cost, no obligation. In-office in Odenton, MD or by telehealth.
Questions to bring to your clinician
These questions can help you get the most out of your next visit.
Which labs, such as ferritin, thyroid or cortisol, would help explain my fatigue?
Which labs or assessments would help us understand my fatigue in my case?
Which daily habits are most likely to make a difference for my fatigue for me?
How long would it be reasonable to try these steps for my fatigue before we review them together?
Practitioner-grade options in my Fullscript catalog: if you and your clinician decide a supplement makes sense, my supplement guide by health goal links to the practitioner-grade products I trust.
Frequently asked questions
What are the most common hidden causes of fatigue?
Common causes include low iron stores (ferritin), thyroid issues, disrupted cortisol rhythm, poor sleep or sleep apnea, blood sugar swings, low vitamin D, B12 or magnesium, depression, medication side effects, and ongoing inflammation. Testing helps narrow it down.
Which labs should I ask about for persistent fatigue?
A reasonable starting point is a CBC, ferritin and iron studies, a full thyroid panel, vitamin D, B12, magnesium, and blood sugar markers. Depending on your history, a provider may add cortisol rhythm testing or other functional labs.
Can supplements help with energy?
Some nutrients and botanicals, such as CoQ10, magnesium, B vitamins and adaptogens like ashwagandha or rhodiola, are studied for energy and stress. Evidence varies, and they work best when they match an identified need. Ask your provider about interactions before you start.
When is tiredness a reason to see a doctor right away?
Seek care promptly if fatigue comes with chest pain, shortness of breath, fainting, unexplained weight loss, fever or night sweats, or thoughts of self-harm, or if it is new and severe.
Sources
- Vaucher P, et al. Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. CMAJ 2012. PMID: 22777991. https://pmc.ncbi.nlm.nih.gov/articles/PMC3414597/
- Panossian A, Wikman G. Effects of Adaptogens on the Central Nervous System and the Molecular Mechanisms Associated with Their Stress-Protective Activity. Pharmaceuticals (Basel) 2010. PMID: 27713248. https://pmc.ncbi.nlm.nih.gov/articles/PMC3991026/
- Tardy AL, et al. Vitamins and Minerals for Energy, Fatigue and Cognition: A Narrative Review of the Biochemical and Clinical Evidence. Nutrients 2020. PMID: 31963141. https://pmc.ncbi.nlm.nih.gov/articles/PMC7019700/
- Leproult R, et al. Transition from dim to bright light in the morning induces an immediate elevation of cortisol levels. J Clin Endocrinol Metab 2001. PMID: 11231993. https://pubmed.ncbi.nlm.nih.gov/11231993/
- Blume C, Garbazza C, Spitschan M. Effects of light on human circadian rhythms, sleep and mood. Somnologie (Berl) 2019. PMID: 31534436. https://pmc.ncbi.nlm.nih.gov/articles/PMC6751071/
- MedlinePlus: Fatigue
- MedlinePlus Medical Encyclopedia: Fatigue
- NCCIH: Coenzyme Q10
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
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