- Old Town Scottsdale: (480) 949-9333
- Camelback & 101: (623) 777-1720
- Camelback: (623) 777-1720
- Scottsdale: (480) 949-9333
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Old Town Scottsdale:
Camelback & 101:
Old Town Scottsdale:
Camelback & 101:
Constant tiredness usually has a cause that can be found and treated. The most common medical reasons include sleep disorders, anxiety or depression, thyroid problems, diabetes, anemia, low vitamin levels, hormonal changes, infections, and side effects from medications. “Why Am I Always Tired? Common Medical Reasons for Fatigue” explores these causes, the signs that point to them, and how we work to find what is draining your energy.
Fatigue is an ongoing lack of physical or mental energy that does not go away with rest. Everyone feels tired after a long day or a poor night of sleep, but that kind of tiredness fades once you recover. Medical fatigue lingers for weeks or months and can make work, exercise, and family time feel harder than they should. When rest does not fix it, something else is usually going on in the body.
Fatigue can show up in many ways. Common signs include:
Feeling worn out even after a full night of sleep
Trouble focusing or remembering things
Muscle weakness or heavy limbs
Low motivation or interest in daily activities
Slower reaction times
Irritability or mood changes
Needing naps to get through the day
Pay attention to when your fatigue started and what makes it better or worse. These details help us narrow down the cause.
Some people sleep seven or eight hours and still wake up exhausted. A sleep disorder may be the reason. Sleep apnea causes breathing to pause again and again during the night. Each pause pulls you out of deep sleep, even if you do not remember waking up. Loud snoring, gasping, and morning headaches are common signs.
Insomnia is another frequent cause. People with insomnia have trouble falling asleep, staying asleep, or both. Restless legs syndrome can also break up sleep with an urge to move the legs at night. We evaluate and treat sleep issues and coordinate further testing when it is needed.
Daily routines can affect sleep quality as much as a medical condition. Late caffeine, alcohol before bed, screen time at night, and irregular bedtimes can all lower the quality of your rest. Shift work can also throw off your body clock.
Simple changes can help:
Go to bed and wake up at the same time each day
Stop caffeine by early afternoon
Keep your bedroom cool, dark, and quiet
Put phones and tablets away before bed
If better habits do not improve your energy within a few weeks, a medical cause is more likely.
Stress and anxiety keep the body on high alert. Over time, this constant tension wears down your energy. Anxiety can also make it hard to fall asleep or stay asleep, which adds to daytime tiredness. Many people with anxiety notice racing thoughts, a tight chest, or a sense of dread along with their fatigue. We help patients manage anxiety and stress as part of their overall care.
Depression is a common and often missed cause of fatigue. It can make everyday tasks feel draining. Other signs include sadness, loss of interest in things you used to enjoy, changes in appetite, and sleeping too much or too little. Depression is a medical condition, and it responds to treatment. Talking openly about your mood with your provider is an important step.
When the heart or lungs are not working well, less oxygen reaches your muscles and brain. This can leave you tired and short of breath, especially with activity. Heart disease, heart failure, and chronic lung conditions such as asthma and COPD can all cause fatigue. Feeling winded during tasks that used to be easy is a sign to get checked.
Blood sugar that runs too high or too low affects your energy. With diabetes, the body has trouble moving sugar from the blood into the cells that need it for fuel. Fatigue, extra thirst, frequent urination, and blurry vision are common early signs.
Insulin resistance and prediabetes can cause similar tiredness before diabetes develops. Many patients feel a crash after meals. We offer diabetes management and care for insulin resistance to help steady energy levels.
In autoimmune disorders, the immune system attacks healthy tissue. Conditions such as rheumatoid arthritis, lupus, and celiac disease often cause deep, lasting fatigue. Joint pain, rashes, fevers, and digestive changes may appear along with tiredness. These conditions can be hard to spot because symptoms come and go.
Living with pain every day takes a toll. Arthritis, chronic back pain, and fibromyalgia can disrupt sleep and wear down your body. Pain and fatigue often feed each other. Poor sleep makes pain worse, and pain makes sleep worse. Treating the pain can often improve energy.
The thyroid gland controls how your body uses energy. When it makes too little hormone, a condition called hypothyroidism, everything slows down. Fatigue, weight gain, feeling cold, dry skin, and constipation are common signs. An overactive thyroid can also cause fatigue, along with a racing heart, weight loss, and anxiety.
Thyroid problems are among the most common medical reasons for fatigue, and a simple blood test can check for them. We diagnose and manage thyroid disorders with ongoing lab monitoring.
Other hormone changes can also drain energy. In men, low testosterone may cause fatigue, low libido, muscle loss, and mental fog. In women, perimenopause and menopause can bring fatigue along with hot flashes, night sweats, and poor sleep.
We offer medically supervised testosterone replacement therapy and personalized hormone replacement therapy for men and women. Both are guided by lab testing and ongoing monitoring. Learn more about our care for hormonal imbalances.
Your body needs certain nutrients to make energy. Low levels of these nutrients are a frequent and very treatable cause of fatigue.
Iron: Low iron can lead to anemia, which means your blood carries less oxygen. Signs include fatigue, pale skin, and shortness of breath.
Vitamin B12: Low B12 can cause tiredness, tingling in the hands or feet, and memory problems. It is more common in older adults, vegetarians, and people taking certain medications.
Vitamin D: Low vitamin D is linked to fatigue, muscle aches, and low mood.
Folate and magnesium: Low levels of these can also affect energy.
Blood work is the only reliable way to know if a deficiency is the cause. Taking supplements without testing can hide the real problem.
Carrying extra weight puts more strain on the heart, lungs, and joints. Being underweight can leave the body without enough fuel or nutrients to keep up energy.
We offer physician-guided weight loss support that combines metabolic assessment, nutritional guidance, and lifestyle support. When appropriate, FDA-approved medications are part of the plan. Reaching a healthier weight often brings a noticeable boost in energy.
Eating disorders such as anorexia, bulimia, and binge eating disorder can deeply affect energy. Not getting enough calories or nutrients leaves the body running on empty. These conditions also affect the heart, hormones, and mood. Anyone struggling with food and eating deserves a supportive medical evaluation.
Many infections cause fatigue while the body fights them off. The flu, COVID-19, and other respiratory infections are common examples. Some infections, such as mononucleosis, can cause tiredness that lasts for weeks or even months after other symptoms fade.
Fatigue after an illness usually improves with time. If it lasts longer than expected or comes with fever, swollen glands, or weight loss, an evaluation is a good idea. We offer prompt sick visits for infections, flu, and other non-emergency illnesses.
Many common prescriptions list fatigue as a side effect. These include some blood pressure medicines, antidepressants, antihistamines, sleep aids, muscle relaxants, and pain medications. Taking several medications at once raises the chance of side effects and interactions.
We offer careful medication management. We review everything you take to find possible causes of fatigue and adjust your plan when needed. Never stop a prescription on your own. Talk with your provider first.
Alcohol, cannabis, and some over-the-counter products can affect sleep and energy. Withdrawal from caffeine or nicotine can also cause short-term tiredness. Medical treatments such as chemotherapy and radiation commonly cause fatigue. Sharing a full list of everything you use helps your provider see the whole picture.
Make an appointment if your fatigue:
Lasts more than two to three weeks
Does not improve with rest or better sleep habits
Gets in the way of work, school, or daily life
Comes with unexplained weight loss or gain
Appears with fever, night sweats, or swollen glands
Comes with changes in mood, appetite, or sleep
Seek emergency care right away by calling 911 if fatigue comes with chest pain, severe shortness of breath, fainting, sudden weakness on one side of the body, or thoughts of self-harm.
Finding the cause of fatigue starts with a detailed conversation. Your provider will ask about your sleep, diet, stress, mood, medications, and medical history. A physical exam follows.
Because fatigue can have more than one cause, we are trained to evaluate multiple symptoms and overlapping conditions. Punnaiah Marella, MD and Shantipriya Siripurapu, MD are board-certified internists through the American Board of Internal Medicine. They work with our physician assistants to sort through complex cases. Our Complex Diagnosis service is built for this kind of detective work.
Common tests include:
Complete blood count: Checks for anemia and signs of infection
Thyroid panel: Measures thyroid hormone levels
Blood sugar and A1C: Screens for diabetes and prediabetes
Metabolic panel: Reviews kidney function, liver function, and electrolytes
Vitamin levels: Checks iron, B12, vitamin D, and folate
Hormone testing: Measures testosterone or other hormones when symptoms suggest an imbalance
Inflammation markers: Helps screen for autoimmune conditions
We offer on-site phlebotomy, so blood draws happen during your visit rather than at a separate lab. You can read more about our Lab Tests. If results point to a condition that needs a specialist, we manage the referral and review results with you.
Treatment depends on the cause. Correcting a vitamin deficiency, adjusting a medication, treating a thyroid disorder, or managing blood sugar can each restore energy. Hormone therapy may help when low testosterone or menopause is the source. Better sleep habits, regular movement, balanced meals, and stress management support every treatment plan.
Many patients have more than one factor at play. A long-term relationship with a primary care team helps track changes over time and adjust care as your needs evolve.
The answer to “Why Am I Always Tired? Common Medical Reasons for Fatigue” is rarely just a busy schedule. Ongoing tiredness is your body’s signal that something needs attention. If fatigue has lasted more than a few weeks, we can help find the cause through a careful exam and targeted lab work. Visit our Fatigue page to learn more about how we approach this concern.
Fatigue is common, but it is not something you have to accept. Most causes can be identified with a thorough evaluation and treated with a plan built around you.
Author
Phoenix Internal Medicine
October 16, 2026
Scottsdale:
Camelback: