Why Am I Always Tired? Could Your Genes and Gut Hold Some Clues?

You wake up tired. By mid-afternoon, you’re reaching for another coffee. And even when you get to bed earlier, you don’t always feel refreshed.

If you’ve been asking, “Why am I always tired?”, you’re not alone. But the answer isn’t necessarily as simple as needing more sleep—or another supplement.

Persistent tiredness can have many contributing factors. Your sleep, nutrition, stress, medications and overall health all deserve consideration. Your genetics and gut microbiome may add context, too.

Understanding where these pieces fit can help you take a more informed approach to your energy.

Why Am I Always Tired? Start With the Common Causes

Before looking at your genes or gut bacteria, it’s important to consider more familiar explanations.

Insufficient or disrupted sleep, stress, depression, hormonal changes, illnesses and certain medications can all contribute to tiredness. Medical conditions such as sleep apnoea, iron deficiency anaemia, diabetes and thyroid disorders may also be involved. If fatigue lasts for several weeks, has no clear explanation or affects your daily life, speak with a healthcare professional.

That assessment comes first. Wellness testing can provide additional information, but it cannot replace an investigation into persistent fatigue.

Could Nutrient Deficiencies Be Affecting Your Energy?

Your body depends on an adequate supply of nutrients to function. When something is missing, fatigue can be one of the symptoms.

Iron helps your body make haemoglobin, the protein that carries oxygen in red blood cells. Iron deficiency anaemia can cause tiredness, weakness and difficulty concentrating. Your risk can be influenced by factors such as dietary intake, absorption and blood loss, including heavy menstrual bleeding.

Vitamin B12 supports healthy blood cells and nerve function. A deficiency can cause fatigue and weakness, sometimes alongside neurological symptoms such as numbness or tingling. Both inadequate intake and problems absorbing B12 can contribute.

However, feeling tired doesn’t tell you which nutrient—if any—is low.

Taking iron or high-dose vitamins without understanding the cause may miss the underlying issue. A healthcare professional can assess your symptoms, diet and medical history and decide whether bloodwork is appropriate.

Where Do Your Genes Fit In?

Genetic differences can influence some of the biological processes involved in how your body handles nutrients.

Folate metabolism is one example.

The MTHFR gene provides instructions for an enzyme involved in processing folate. Certain common variants can reduce the enzyme’s activity and influence folate-related biology. But having an MTHFR variant does not automatically mean you have a deficiency, cannot process folic acid or need a particular supplement.

It also doesn’t establish why you feel tired.

The useful distinction is:

A genetic tendency tells you something about an inherited characteristic. It does not measure your current nutrient status.

For example, a genetic result related to folate metabolism and a blood test assessing folate status answer different questions. Your diet, medications, health conditions and other factors help determine what that information means for you.

Genetic insights are most useful when interpreted alongside this wider context.

Could Your Coffee Habit Be Part of the Picture?

Do you know someone who can drink coffee after dinner and sleep soundly, while an afternoon cup leaves you wide awake?

Part of the difference may be genetic.

Your liver breaks down caffeine primarily using an enzyme called CYP1A2. Genetic differences can influence this enzyme’s activity, contributing to how quickly your body clears caffeine. Hormones, medications, smoking and other factors also affect that process.

When caffeine takes longer to clear, its effects may extend further into the evening, potentially interfering with sleep and contributing to tiredness the following day.

How quickly you metabolize caffeine is also different from how sensitive you are to it. Genetic differences affecting the brain’s response to caffeine—including variations in ADORA2A—can influence its effects on sleep.

This can create a frustrating pattern: you reach for coffee because you’re tired, but caffeine may interfere with the sleep you need to feel more rested.

Genetic insights can offer additional context for your caffeine response. Your everyday experience matters, too: how much you drink, when you drink it and whether moving your last cup earlier helps you sleep better.

The goal is to find an approach to caffeine that supports your energy throughout the day—and your sleep at night.

Can Your Gut Microbiome Affect Your Energy?

Digestive symptoms aren’t always limited to your stomach. People with irritable bowel syndrome (IBS), for example, can also experience fatigue—highlighting the importance of looking beyond digestion alone.

A 2026 randomized, placebo-controlled trial involving 61 adults with diarrhoea-predominant IBS examined a specific probiotic strain, Bifidobacterium breve Bif195. After eight weeks, participants receiving the probiotic had a greater reduction in fatigue scores than those receiving the placebo.

The improvement in fatigue was an exploratory finding, and the probiotic did not improve the study’s main measure of IBS symptom severity. Still, it provides an example of human research exploring how a gut-directed intervention may influence how people feel beyond their digestive symptoms.

For someone experiencing both digestive discomfort and low energy, gut health deserves consideration as part of a broader assessment.

The useful question is: could your digestive health be one of several factors worth exploring?

Your symptoms, nutrition, sleep, medical history and gut microbial ecosystem can each contribute different information. Considering them together helps build a more personalized understanding of your health.

What Can Gut Microbiome Testing Tell You?

Gut microbiome testing explores the community of microorganisms living in your digestive tract.

dnaPower’s MapmyBiome uses advanced metagenomic sequencing to identify microorganisms in your stool sample and provide insights into microbial diversity, beneficial and potentially opportunistic organisms, and their potential functions.

These insights can help inform personalized nutrition and lifestyle recommendations.

While genetic testing explores your inherited tendencies, microbiome testing examines your gut microbial ecosystem, which can change over time with diet, lifestyle, medications and other factors.

Microbiome testing adds another perspective on your health, but it cannot diagnose the cause of persistent fatigue.

DNA Testing, Blood Testing and Microbiome Testing Answer Different Questions

It’s easy to group health tests together, but they provide different types of information.

For persistent tiredness, your symptoms and clinical assessment should guide the investigation. Additional wellness insights should support that process.

A Practical Starting Point When You Feel Tired All the Time

You don’t need to overhaul everything at once. Start by gathering information that can make the next step clearer.

1. Notice Your Pattern

Does your tiredness begin when you wake up, build throughout the day or follow particular meals? Has it changed recently?

A brief record of sleep, meals, caffeine, medications and symptoms can help you explain what you’re experiencing.

2. Review Your Everyday Foundations

Consider whether you’re giving yourself regular opportunities to sleep, eating enough and relying on caffeine to get through the day.

This isn’t about achieving a perfect routine. It’s about identifying practical changes that may be worth discussing or trying.

3. Seek Assessment for Persistent Fatigue

If you have been tired for several weeks or it is affecting your normal activities, arrange a healthcare appointment. Mention accompanying symptoms, including snoring, changes in weight, heavy periods or changes in mood.

4. Put Additional Testing in Context

If you’re interested in genetic or microbiome testing, be clear about the question you want it to answer.

These insights can help you make more informed nutrition and lifestyle choices as part of a broader approach to understanding your energy.

How dnaPower Fits Into a Personalized Approach

Once appropriate medical assessment is underway, you may want to learn more about your individual biology.

dnaPower’s totalPower DNA test explores genetic variations associated with nutrition, metabolism, caffeine response, methylation and other areas of wellness. These insights can provide context for conversations about your food and lifestyle choices.

MapmyBiome provides a different perspective by examining your gut microbial ecosystem.

Together, these tests offer additional insights into your individual biology, helping inform a more personalized approach to nutrition and lifestyle alongside your symptoms, health history and clinical findings.

Because the most useful approach to feeling better begins with understanding what deserves attention in your situation.

Explore totalPower DNA Testing
Learn More About MapmyBiome

Frequently Asked Questions

Why am I always tired even when I get enough sleep?

Time spent in bed does not necessarily reflect sleep quality. Disrupted sleep, sleep apnoea, stress, medications and medical conditions are among the possible explanations. Persistent tiredness deserves assessment rather than assuming more sleep is the only answer.

Can a DNA test tell me why I’m tired?

A DNA wellness test cannot diagnose the cause of fatigue. It can identify selected inherited variants related to areas such as nutrient metabolism, which may provide additional context when considered alongside your current health.

Does an MTHFR variant cause fatigue?

A common MTHFR variant does not, by itself, establish a cause of fatigue. Some variants influence folate metabolism, but your actual nutrient status and overall health require separate consideration.

Should I take B12 if I’m tired?

B12 deficiency can cause fatigue, but tiredness alone does not confirm a deficiency. B12 supplements have not been shown to improve energy in people who already have adequate B12 intake and status. Assessment can help determine whether supplementation is appropriate.

Can a gut microbiome test diagnose chronic fatigue syndrome?

No. A commercial gut microbiome test cannot diagnose ME/CFS. Research findings about microbial differences are not equivalent to a validated diagnostic test.

References

1. NHS. Tiredness and fatigue.

2. National Institutes of Health, Office of Dietary Supplements. Iron: Fact Sheet for Consumers.

3. National Institutes of Health, Office of Dietary Supplements. Vitamin B12: Fact Sheet for Consumers.

4. Centers for Disease Control and Prevention. MTHFR Gene Variant and Folic Acid Facts.

5. National Institutes of Health, Office of Dietary Supplements. Folate: Fact Sheet for Health Professionals.

6. Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine. 2013;9(11):1195–1200. doi:10.5664/jcsm.3170.

7. Guo C, et al. Deficient butyrate-producing capacity in the gut microbiome is associated with bacterial network disturbances and fatigue symptoms in ME/CFS. Cell Host & Microbe. 2023;31(2):288–304.e8. doi:10.1016/j.chom.2023.01.004.

8. Xiong R, et al. Multi-’omics of gut microbiome-host interactions in short- and long-term myalgic encephalomyelitis/chronic fatigue syndrome patients. Cell Host & Microbe. 2023;31(2):273–287.e5. doi:10.1016/j.chom.2023.01.001.