Why Am I Tired All the Time? Common Causes of Fatigue
Feeling tired after a busy week or a poor night of sleep is normal. But what if you’re getting enough sleep and still feel exhausted?
Persistent fatigue is one of the most common concerns people bring to primary care. It can affect concentration, motivation, exercise, work, and your overall quality of life. Sometimes the explanation is relatively simple. Other times, fatigue can be a sign that something else is going on.
The important thing is that fatigue is a symptom—not a diagnosis. Finding the cause often starts with looking at the bigger picture.
Are You Actually Getting Enough Quality Sleep?
The first question is usually the most obvious: How are you sleeping?
Adults generally need at least seven hours of sleep each night, but the number of hours isn't the whole story. You can spend eight hours in bed and still wake up tired if your sleep is frequently interrupted or poor quality. Possible sleep-related causes of fatigue include:
Insomnia
Sleep apnea
Restless legs
Frequent nighttime awakenings
Irregular sleep schedules
Alcohol use near bedtime
Certain medications
Snoring, waking with headaches or a dry mouth, frequently waking during the night, or feeling excessively sleepy during the day can be clues that your sleep deserves a closer look.
When sleep apnea or another sleep-related breathing problem may be contributing to fatigue, Avaly Direct Health offers at-home SleepImage sleep studies for $45. The small wearable device allows patients to complete the study at home and provides information that can help determine whether sleep apnea may be affecting sleep quality and daytime energy. Are You Actually Getting Enough Quality Sleep?
Anemia and Iron Deficiency
Your red blood cells carry oxygen throughout your body. When you have anemia—or sometimes even low iron before significant anemia develops—you may experience fatigue, weakness, headaches, dizziness, shortness of breath, or reduced exercise tolerance.
Iron deficiency can be related to heavy menstrual bleeding, diet, pregnancy, gastrointestinal blood loss, or difficulty absorbing iron.
A complete blood count (CBC) and, when appropriate, iron studies can help determine whether anemia or iron deficiency may be contributing to your symptoms.
Thyroid Problems
Your thyroid helps regulate metabolism, energy, temperature, heart rate, and many other body functions. An underactive thyroid, known as hypothyroidism, can cause symptoms such as:
Fatigue
Weight gain
Feeling unusually cold
Constipation
Dry skin
Hair changes
Muscle aches
Difficulty concentrating
Because these symptoms overlap with many other conditions, thyroid problems can't be diagnosed based on symptoms alone. Blood testing such as TSH and, when appropriate, additional thyroid testing can help evaluate thyroid function.
Vitamin and Nutrient Deficiencies
Certain nutritional deficiencies can contribute to low energy. Depending on your symptoms, diet, medications, and medical history, your provider may consider evaluating nutrients such as:
Vitamin B12
Folate
Vitamin D
Testing everything isn't necessarily better. The goal should be to choose testing based on your individual symptoms and risk factors rather than ordering a long list of labs without a reason.
Blood Sugar and Metabolic Health
Changes in blood sugar can sometimes contribute to fatigue. Insulin resistance, prediabetes, and diabetes may develop gradually. Some people have no obvious symptoms, while others notice low energy, increased thirst, frequent urination, increased hunger, or changes in weight. Tests such as fasting glucose and hemoglobin A1C can provide useful information about blood sugar and metabolic health.
Hormonal Changes
Hormones can also influence energy, sleep, mood, muscle mass, and overall well-being.
For women, perimenopause and menopause may contribute to fatigue through hormonal changes, disrupted sleep, hot flashes, mood changes, or changes in menstrual bleeding. For men, low testosterone can sometimes contribute to fatigue, although low energy alone does not mean someone has low testosterone.
Hormone testing is most useful when symptoms and medical history suggest there may be a reason to investigate further.
Medications Can Make You Tired
Fatigue can also be a side effect of medications. Common examples can include certain:
Antihistamines
Sleep medications
Anxiety medications
Antidepressants
Blood pressure medications
Muscle relaxants
Pain medications
Don't stop a prescribed medication without discussing it with your healthcare provider. Instead, review your medication list—including supplements and over-the-counter products—to see whether something could be contributing.
Stress, Anxiety, and Mental Health
Physical and mental health are closely connected. Chronic stress, anxiety, depression, burnout, and major life changes can all cause very real physical fatigue. They can also interfere with sleep, appetite, exercise, and concentration.
That doesn't mean persistent fatigue should automatically be attributed to stress. A good evaluation considers both physical and mental health rather than assuming one or the other is responsible.
Other Medical Causes of Fatigue
Fatigue can occur with many other conditions, including infections, autoimmune disorders, heart or lung disease, kidney or liver problems, chronic pain, and other medical conditions.
That's one reason persistent fatigue deserves an individualized evaluation rather than simply adding another cup of coffee.
What Blood Tests Can Help Evaluate Fatigue?
There isn't one single "fatigue test." Depending on your symptoms and medical history, a primary care provider may consider testing such as:
Complete blood count (CBC)
Comprehensive metabolic panel (CMP)
Thyroid testing
Iron and ferritin
Vitamin B12 or folate
Vitamin D
Hemoglobin A1C or glucose
Additional testing based on your symptoms
Not everyone needs every test. Your symptoms, physical exam, medications, health history, family history, sleep, and lifestyle should help determine which tests actually make sense.
When Should You See a Healthcare Provider?
Consider making an appointment if fatigue is persistent, unexplained, getting worse, or interfering with your normal activities. Seek more urgent medical attention when significant fatigue occurs with concerning symptoms such as chest pain, difficulty breathing, fainting, significant bleeding, severe weakness, confusion, or other sudden or severe symptoms.
Finding the Cause Matters
If you're tired all the time, the goal shouldn't simply be to find something that gives you more energy. The better question is: Why are you tired?
Sometimes the answer is sleep or lifestyle. Sometimes bloodwork identifies anemia, a thyroid problem, metabolic changes, or a nutritional deficiency. And sometimes the evaluation points in another direction entirely.
At Avaly Direct Health in Englewood, Colorado, we take the time to look at the whole picture—including symptoms, sleep, medications, lifestyle, medical history, and appropriate laboratory testing—to help determine what may be contributing to persistent fatigue.
Serving Englewood and the Denver area with primary care focused on accessible, personalized care.
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