Why Am I Always Tired? 10 Common Medical Causes of Fatigue in Women

(Tina Dawn/ VM Med) — In this fast-paced world, it’s not unusual for many of us to rarely feel well-rested. Feeling constantly exhausted, even after a full night’s sleep, is one of the most common concerns women bring to their doctors. While occasional tiredness is normal in today’s fast-paced world, persistent or chronic fatigue is often a sign of an underlying medical issue, particularly in women.

Women are more likely than men to experience ongoing fatigue due to hormonal changes throughout life, including menstruation, pregnancy, perimenopause, and menopause. Women also have a higher prevalence of certain medical conditions that affect energy levels, and many continue to balance professional responsibilities with caregiving and household duties.

There are many complex reasons why women might feel chronically lacking in energy. Here are the ten most common causes, in no particular order.  

As a private medical clinic specializing in women’s health, we frequently see patients asking, “why am I always tired?”. Below are the 10 most common medical and lifestyle-related causes of fatigue in women, and when it’s time to seek medical care.

1. Iron-Deficiency Anemia

Iron-deficiency anemia is one of the leading causes of fatigue in women, especially those of reproductive age. Even mildly low iron levels can cause:

• Persistent tiredness
• Brain fog
• Weakness
• Shortness of breath

Women are at higher risk due to menstrual blood loss and increased iron demands during pregnancy. Anemia is often overlooked because symptoms can mimic everyday stress or lack of sleep. Blood testing is the only way to confirm iron deficiency. Yale Medicine advises women to know some key points about iron deficiency.

2. Sleep Apnea

Sleep apnea is a condition that causes repeated interruptions in breathing during sleep, leading to poor sleep quality and daytime exhaustion. 

Risk factors in women include:

• Menopause
• Pregnancy
• Polycystic Ovary Syndrome (PCOS)
• Obesity (men and women)

While more men suffer from sleep apnea, it is frequently underdiagnosed or misattributed to stress or anxiety in women. Untreated sleep apnea increases the risk of heart disease, high blood pressure, stroke, and Type 2 diabetes.

3. Hormonal Changes

Hormones play a critical role in regulating energy, sleep, and metabolism. Fatigue is common during:

• Menstruation
• Pregnancy
• Perimenopause
• Menopause

These hormonal changes can also affect a woman’s metabolism and sleep patterns, which go on to affect overall energy levels. Night sweats, hot flashes, and disrupted sleep during perimenopause and menopause often lead to chronic exhaustion. Pregnant women also experience major hormonal surges, and fatigue is quite normal when so much of your body’s energy is being expended on creating a baby. Hormonal balance can also be influenced by diet, stress, exercise, and alcohol intake.

4. Thyroid Issues

Thyroid conditions are especially common in women and often present first as unexplained fatigue.

• Hypothyroidism (underactive thyroid): Causes sluggishness, weight gain, cold intolerance, and low energy.
• Hyperthyroidism (overactive thyroid): Can cause anxiety, insomnia, heart palpitations, and exhaustion from poor sleep.

Thyroid disorders are very common in middle-aged women and often initially manifest as fatigue you can’t seem to shake off. With proper diagnoses and treatment, most women see a significant improvement in energy levels.

5. Lifestyle Factors That Drain Energy

One’s own personal lifestyle choices can severely impact energy levels. Certain daily habits can drain your energy include:

• Poor nutrition
• Excess alcohol or caffeine
• Inadequate sleep
• Sedentary lifestyle

Mental health also plays a major role. Chronic stress and anxiety keep the body in a constant state of alert, preventing proper rest and recovery.

6. Diabetes

Fluctuations in blood sugar, both high and low, can cause intense fatigue. It takes a lot for our bodies to convert glycose into energy, so if we are too high or low, we need to use more energy for regulation. 

Diabetes may also lead to:

• Poor sleep
• Dehydration
• Difficulty converting glucose into usable energy 

Managing blood sugar through diet, movement, and medical care is essential for restoring energy.

7. Depression and Anxiety

Fatigue is one of the most common symptoms of depression and anxiety. In a study from 2018 cited in Medical News Today, over 90% of people with major depressive disorder experience chronic fatigue. 

In women, depression-related fatigue may stem from:

• Sleep disturbances
• Hormonal factors
• Medication side effects

This can create a vicious cycle that can be hard to break. The fatigue experienced by those dealing with depression can be attributed to poor sleeping patterns, oversleeping, hormones, and medication side effects. Treatment often includes therapy, lifestyle changes, and medication, which can significantly improve energy and quality of life.

8. Vitamin Deficiencies (B12 and Vitamin D)

If you’re feeling like you’re constantly running on empty, it might be worth asking your doctor to check your vitamin levels. Low levels of certain vitamins are a frequent, and easily treatable, cause of fatigue.

• Vitamin B12 deficiency: Can lead to anemia, weakness, and cognitive fog.
  
• Vitamin D deficiency: Common in Canada, especially during winter months, and linked to fatigue, muscle weakness, and low mood.
  

Without Vitamin B12 your body can’t produce healthy red blood cells, and a lack of it may cause anemia. A diet that includes meat and dairy products is a good way to get B12, but as people get older they have a harder time absorbing the vitamin, and vegetarians and vegans may find themselves deficient as well. Sunlight is the best way to ensure you get enough Vitamin D, which ensures bone and muscle strength. Tuna and salmon are also good sources of the vitamin, while supplements can also help.

Blood tests can quickly identify deficiencies, and supplementation is often highly effective.

9. Chronic Illness and Autoimmune Conditions

Energy levels can be affected by conditions such as:

• Lupus
• Rheumatoid arthritis
• Fibromyalgia
• Inflammatory bowel disease (IBD)
• Multiple sclerosis

These conditions often cause profound fatigue, especially when chronic pain or inflammation disrupts sleep.

Post-viral fatigue, including long COVID, is also increasingly recognized as a cause of persistent exhaustion in women. According to the Mayo Clinic, common symptoms of long Covid include extreme tiredness, especially after activity, memory loss, brain fog, and a feeling of being lightheaded or dizzy.

10. Stress and Burnout

Very common in our fast-paced world, stress and burnout are caused by your body constantly remaining in fight mode, always in overdrive. When this happens your cortisol levels increase, your immune system is weakened, you don’t sleep well, and your mental and physical energy is depleted, leading to an eventual burnout. 

Women are particularly vulnerable to burnout when they consistently prioritize others’ needs over their own. Without adequate rest and boundaries, prolonged stress can lead to complete emotional and physical exhaustion.

How VM Med Private Clinic in Montreal Can Help

VM Med’s Thyroid Centre supports patients through every stage of thyroid health—from diagnosis to long-term management. Your thyroid is one of the endocrine glands which make hormones to regulate physiological functions in your body, including energy levels.

Thyroid & Endocrine Expertise

Since 2021, Dr. Cassandre Benay, MD, MSc, FRCS(C), Breast and Thyroid Specialist and Endocrine Surgeon, has been practicing at VM Med. Dr. Benay completed his medical and surgical training at McGill University and specialized in endocrine surgery at the Cleveland Clinic, one of the world’s leading centers. Our medical team addresses the root causes of fatigue, not just the symptoms.

At VM Med Private Clinic we offer:

• Women-specific healthcare
• A welcoming, discreet environment
• Specialized counseling and diagnostics
• Personalized treatment plans

Feeling Constantly Tired?

Persistent fatigue is not something you should ignore or simply “push through.” For more information, explore our VM Med blog, including:

• PCOS & More: Understanding Hormonal Imbalances in Women
• How The Thyroid Impacts Women, Hormones, and Menstruation

Or, Book a consultation with our medical experts to uncover what’s really behind your fatigue.