Everyone feels tired sometimes. A late night, stressful week, interrupted sleep, travel, parenting, work demands, or simply not getting enough recovery can all explain why someone feels run down.
But when fatigue becomes persistent, disruptive, or hard to explain, it may be worth looking deeper. Learn how to tell the difference between normal tiredness and fatigue, how fatigue is a signal of your overall well-being, and blood testing, lifestyle assessment, and whole body imaging may provide helpful further context about what may be happening beneath the surface.
Tiredness is common
Fatigue is one of the most common symptoms that sends people to the doctor, according to research. Tell someone you’re tired today, and they’ll relate right away. Fatigue can be both physical or mental, each one having an effect on the other. What it boils down to is the feeling that you can’t keep up with the demands of your day.
For most, periods of low energy are the result of factors such as:
- Sleep problems (too little sleep, poor sleep quality)
- Stress
- Travel
- Overtraining
- Under-eating or a poor diet
- Dehydration
- Alcohol use
- Life demands, such as at work or caregiving
Frequently, fatigue is straightforward. You’ve been staying up too late, a couple of alcoholic drinks disrupted your sleep, or you’re not drinking enough water. In that case, making pointed changes to your lifestyle can improve your energy levels.
How to differentiate between “normal tired” and something more
Tiredness is subjective. In fact, it goes by many different names. You can be fatigued, weak, lack energy, or even have trouble focusing. Oftentimes, we feel as if we just need to get more sleep and those instincts are correct. Normal tiredness improves after getting rest, has an obvious cause (you went out last night, you’ve been up late working), is intermittent—not everyday, and improves as you change your lifestyle.
On the other hand, fatigue can point to something more going on in your body when it doesn’t resolve with lifestyle change like improved sleep. Talk to your doctor if you have fatigue that:
- Interferes with daily life and function by making everyday activities difficult
- Affects your mood
- Feels disproportionate to your physical or mental activity level
- Developed alongside additional unexplained red flag symptoms, such as changes in weight or appetite, shortness of breath, dizziness, fevers/night sweats, or pain
Chronic fatigue is defined as fatigue that persists for six months or more. However, you don’t have to wait that long before investigating. Even days or weeks of unexplained tiredness is a good reason to talk to a healthcare provider.
Sleep disorders
The recommended amount of sleep for an adult is between seven and nine hours. If you’re logging that much but are still tired or have poor sleep quality, your healthcare provider might want to evaluate you for a sleep disorder. Here’s why: Conditions like obstructive sleep apnea—where you have shallow breathing or mini pauses in breathing throughout the night—are common and come with severe health consequences, including an increase in blood pressure, heart disease, diabetes, and dementia risk. Other sleep conditions include insomnia, restless legs, and narcolepsy.
It’s possible that your provider may recommend you to a sleep clinic for a sleep apnea test. In addition, bloodwork and imaging may also help rule out other health conditions, as well as assess heart and metabolic health status.
Related: How poor sleep affects your body
Low nutrient levels
When you think about energy and nutrition, is the first nutrient that comes to mind iron? You’re correct that it plays a pivotal role in keeping your vigor up. Low iron, which is most common in people with heavy periods, pregnant women, frequent blood donors and people with cancer, GI disorders, or heart failure, can manifest as symptoms like GI upset, weakness, tiredness, and brain fog.
However, there are several additional nutrients involved in energy metabolism that keep your mental and physical stamina up: B vitamins (such as folate and B12), magnesium, and zinc. Vitamin D is also emerging as a nutrient implicated in fatigue.
Underlying health conditions, dietary patterns, athletic activity, and medications can increase the risk of nutrient deficiencies associated with fatigue.
Blood panels are a quick way to evaluate nutrient levels, iron status, and complete blood count to assess all of the above. At that point, you can create a plan with your healthcare provider, which may involve diet changes and/or supplements.
Thyroid dysfunction
Your thyroid is a butterfly-shaped gland at the base of your neck that churns out hormones involved in energy regulation. Having a low (underactive) thyroid causes your body to slow down, and as a result, you’re hit with symptoms like fatigue, weight gain, facial puffiness, constipation, dry skin and hair, a slower heart rate, and a low mood.
Although you’d expect that hyperthyroidism (overactive thyroid) might make you unreasonably peppy as your body’s functions speed up, running on high can be draining. Research indicates that during hyperthyroid episodes, people tend to experience mental fatigue and depression.
To diagnose a thyroid problem, blood tests are key. Prenuvo’s blood biomarker lab testing has an Executive Panel that measures many biomarkers, including a Thyroid Panel with TPO Antibodies to identify thyroid dysfunction and thyroid autoimmune disease.
Blood sugar swings and insulin resistance
After you eat, your body releases insulin, the hormone that pushes glucose from your blood into your body’s cells, which is then used for energy. If there’s a problem with this system, such as growing insulin resistance in prediabetes or high blood sugar in type 2 diabetes, you can feel fatigued, sometimes extreme fatigue.
It’s common for prediabetes and diabetes to go unrecognized and undiagnosed. Unless, that is, you have your blood sugar levels checked regularly. That can be done with an A1c test, available in all of Prenuvo’s Blood Panels. Body Composition Analysis also helps provide insight into visceral fat and lean mass, which are also critical for overall metabolic health.
Related: What your bloodwork says about your health
Chronic inflammation
Chronic inflammation is a popular phrase in the health-sphere, and one that’s often misunderstood. It’s defined as “slow, long-term inflammation lasting several months to years.” Infection, autoimmune disease, stress, obesity, and low sex hormones are some of the associated factors behind chronic inflammation. Long-term inflammation is considered dangerous, as it contributes to damage across your body’s systems.
Symptoms of chronic inflammation include chronic fatigue, insomnia, depression, anxiety, GI problems like constipation, diarrhea, or acid reflux, changes in weight, muscle or joint pain, and frequent infections. Not all problems are the result of chronic inflammation, and it’s not a disease in itself. Rather, it’s the result of underlying body processes. In other words: You’ll need to dig deeper to identify why the inflammation showed up—and stuck around—in the first place.
Hormonal changes
Both women and men go through hormonal changes. Women start perimenopause in their mid- to late-40s (though it can happen earlier), a life stage when their estrogen and progesterone levels fluctuate, causing a long list of potential symptoms. Of these, fatigue and physical and mental exhaustion have been reported to affect almost seven out of eight women.
For men, low testosterone may also lead to sluggishness, as the hormone affects cellular energy. That said, hormones are one possible contributing factor to fatigue.
Blood testing provides insight into hormone levels. Prenuvo’s Executive Panel evaluates Female Hormone Markers (FSH/LH, estradiol, progesterone, AMH, low testosterone), while Male Hormone Markers assess androgens like testosterone (total, free, and bioavailable).
Liver, kidney, and organ health
Fatigue can sometimes be related to broader organ function. This can come as a surprise. For example, chronic kidney disease (CKD) is often asymptomatic, though it affects four in 10 adults with diabetes. As the disease advances, people who have CKD can feel fatigued and weak, experience sleep problems, brain fog, and loss of appetite. “Fatty liver,” or MASLD, affects 100 million people in the U.S. alone, and is a disease that can progress to cirrhosis or even liver cancer. Like kidney damage, liver fat and inflammation often causes no initial symptoms, though some people may feel fatigue, weak, or experience abdominal pain as early signs.
For insight into your organ health, several tests can be helpful. Whole body MRI can help provide structural visibility across major organ systems. Bloodwork, such as liver enzymes, can help indicate organ and metabolic health. Whole body MRI and blood labs together may support a detailed conversation and promote needed follow-up with a healthcare provider.
Body composition, low muscle mass, increased visceral fat
Body weight does not always reflect metabolic health, which is why body composition can be a more reliable measure. Low muscle mass can affect strength, energy, and resilience. Higher levels of visceral (abdominal fat) impairs your metabolic health. And given that muscle loss is a natural phenomenon with age, your body composition can shift unfavorably over time. Even thin people are vulnerable to elevated cardiovascular risks if they have excess visceral or liver fat, research shows.
All that to say: Know your body composition. Body Composition Analysis can help assess visceral fat, muscle mass, and muscle asymmetries, providing context that standard weight, waist circumference, or BMI cannot.
Related: Why you should be tracking your body composition
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Mental health, stress, and burnout
You know the feeling at the end of a stressful day. You’re mentally and physically spent. Chronic stress is when those days pile up, one right after the other. Similarly, fatigue is largely considered a core symptom of anxiety and depression. People with anxiety or depression tend to get tired easily (even when they haven’t exerted themselves), and can last even after treatment. This relationship tends to be a two-way street. Mental health conditions can cause fatigue, but fatigue that goes unchecked can develop into more serious burnout.
Related: How stress affects your entire body
Medications, alcohol, caffeine, and other lifestyle habits
Taking care of your health means stepping back sometimes for a birds-eye view of your lifestyle. Several habits, including drinking alcohol, consuming too much caffeine or caffeine late in the day, under-fueling (not consuming enough calories for your body’s needs), overtraining, or skimping on water contribute to fatigue or lack of energy in different and cumulative ways. In addition, some medications can directly or indirectly promote fatigue, including some antihistamines and antidepressants, sedatives, and blood pressure medications like beta blockers.
Fatigue can have many causes, which is why context matters
Blood panels can help reveal functional changes in areas such as nutrient status, thyroid function, metabolic health, inflammation, hormones, and organ function. Whole body MRI can help provide structural visibility across major organ systems. Body Composition Analysis can add insight into visceral fat, muscle mass, and metabolic health. If brain fog is a primary symptom, the Advanced Brain Health Scan looks at measures like the structure and vascular health of your brain. Unexplained cardiovascular fatigue or exercise intolerance may benefit from the Advanced Heart Health Scan. Together, these screenings, available through Executive and Comprehensive Memberships or standalone options, can help support a more informed conversation with a healthcare provider.
To learn more about a Prenuvo Membership or standalone services, book a call with the Patient Services Team.
