Fatigue is a common symptom, and there can be many causes.
It’s easy to confuse “fatigue” with “tiredness.” The main difference is that tiredness improves with rest, but fatigue persists even after you rest.
Fatigue is a constant feeling of tiredness, weariness, or a lack of energy for day-to-day activities. It can be a vague symptom, so pinpointing the cause can be challenging.
While fatigue may be related to an underlying medical condition, diet and lifestyle changes can sometimes help.
This article will explore the most common medical and nonmedical reasons that women feel fatigued.
Causes of fatigue
Sometimes, there is a clear medical cause.
Fatigue is a common symptom during your period and is entirely normal. Its severity and duration can vary from person to person, based on several factors.
When estrogen levels decrease, it leads to reduced levels of some neurotransmitters, including acetylcholine, dopamine, and serotonin. These neurotransmitters are important for maintaining healthy sleep and energy levels.
Heavy periods can lead to fatigue because the increased blood loss causes a reduction in iron levels.
When iron levels in the blood are low, less oxygen reaches your cells. This means that your body must work harder to produce the energy it needs.
Premenstrual syndrome, or PMS, symptoms around the time of your period may lead to sleep disturbances and then fatigue.
During menopause, levels of certain hormones, such as estrogen and progesterone, fluctuate.
Fluctuations in hormone levels can also affect your sleep pattern, resulting in fatigue during the day.
3. Thyroid disorders
Fatigue is one of the main symptoms of an underactive thyroid, or hypothyroidism. This affects more women than men.
Often, symptoms develop slowly and progress gradually over several years. Other symptoms of hypothyroidism include sensitivity to the cold, joint and muscle pain, depression, and weight gain.
Hyperthyroidism — an overactive thyroid — can also cause fatigue. Additional symptoms include an irregular heart rate, twitching or trembling, swelling in the neck, and weight loss.
4. Iron deficiency anemia
Fatigue is also a symptom of iron deficiency anemia.
Blood loss is a common cause of an iron deficiency. So, heavy periods are a risk factor, due to the loss of blood.
Other possible causes of iron deficiency anemia include:
internal bleeding, for instance, due to a stomach ulcer
gastrointestinal diseases that affect the body’s ability to absorb iron, such as celiac disease
Doctors typically treat iron deficiency anemia with iron supplements, which help restore iron levels.
Also, healthcare professionals often recommend that you add iron-rich foods to your diet. Some sources of iron include fortified breakfast cereals, green leafy vegetables, dried fruits and nuts, and red meat.
Depression is a common mental health condition characterized by persistent feelings of hopelessness, sadness, or emptiness. Fatigue is also a common symptom of depression.
Fatigue during COVID-19 typically feels more intense than regular tiredness. It’s an extreme tiredness that persists even after a restful night’s sleep.
On average, the fatigue lasts 5–8 days, but for some people, it may last 2 weeks or longer.
For those with long COVID, a review of 21 studies found that 13–33% of participants reported fatigue at 16–20 weeks after they had first experienced COVID-19 symptoms.
Fatigue is a common symptom of both type 1 and type 2 diabetes.
There are many ways that diabetes can cause fatigue. Lifestyle factors, nutrition, endocrine issues, and certain medications may be involved.
Because people with diabetes have higher blood sugar levels, less sugar reaches the cells. This can sometimes cause weakness and fatigue.
Also, people with diabetes are more likely to experience depression. And as we mentioned above, fatigue is a common symptom of depression.
8. Chronic fatigue syndrome
Chronic fatigue syndrome is a complex, long-term health condition.
It causes extreme tiredness that doesn’t improve with rest. This may get worse after daily activities involving physical or mental effort.
Scientists don’t know what causes chronic fatigue syndrome. However, many people report symptoms after an infection, such as Q fever or influenza, or infections with coronaviruses or the Epstein-Barr virus.
Sleep disturbances are also common in people with chronic fatigue syndrome, and these may worsen feelings of fatigue.
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Other causes of fatigue
Women may also feel fatigued for many nonmedical reasons. These are below.
9. Not eating the right foods
Research has linked some nutrient deficiencies with feelings of fatigue. This includes deficiencies of vitamin C, iron, magnesium, and some B vitamins.
Having a healthy, diverse, and balanced diet is important to ensuring that you meet your nutritional needs.
Focus on a plant-based diet with a broad range of fruits, vegetables, whole grains, beans and pulses, nuts and seeds, and herbs and spices.
Understanding how your blood sugar and blood fat levels respond to certain foods can help you increase your energy.
The ZOE at-home test analyzes these unique blood sugar and blood fat responses. Along with a breakdown of your gut microbiome, we use this information to help you find the best way to eat for your body.
10. Poor sleep
Both sleep quality (how well you sleep) and sleep quantity (how long you sleep) are important for preventing fatigue.
Experts recommend that adults get 7–9 hours of sleep each night.
Research shows that getting regular exercise improves sleep. Limiting alcohol and caffeine in the hours before bedtime can also promote better sleep.
Look after your gut health. Scientists have found that having a diverse gut microbiome is linked to better quality sleep and more sleep.
Stress can be acute (short term) or chronic (long term). While acute stress is temporary, chronic stress is often linked to persistent feelings of fatigue.
Try and manage stress levels through relaxation techniques, such as yoga, mindfulness, or diaphragmatic breathing.
12. Certain medications
Some medications can cause feelings of fatigue. This includes certain:
For people taking some of these medications, the fatigue may improve over time.
13. Low activity levels
Studies show that regular physical activity reduces feelings of fatigue. Scientists have observed this effect in different populations, including people with multiple sclerosis, cancer, and inflammatory bowel disease.
Aim for 150 minutes of moderate-intensity physical activity each week, including cardio-based and strength-based exercises.
Water is essential for all bodily functions. If you haven’t had enough fluids, you may feel more fatigued than usual.
You may be able to avoid some feelings of fatigue by making sure you're hydrated throughout the day.
Try these tips to help you stay hydrated:
drinking water before each meal
keeping water nearby throughout the day
adding fruits or herbs to your water for flavor
starting your day with a big glass of water
drinking tea and coffee if you like them
eating foods that contain plenty of water, like soup and cucumbers
Fatigue can have a variety of causes.
Some conditions that cause fatigue include thyroid disorders, iron deficiency anemia, diabetes, chronic fatigue syndrome, and COVID-19.
Some other causes of fatigue may involve your diet, sleep, and levels of stress. Lifestyle changes can often improve feelings of fatigue in these situations.
If you’re experiencing continuous fatigue, and it’s affecting your quality of life, speak with your healthcare provider to rule out different causes.
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