11 Surprising Causes of Fatigue

A middle-aged woman lies on a couch exhausted. Fatigue is caused by many things including poor sleep hygiene habits, lack of exercise and some conditions.

We all feel tired some of the time, and often it’s nothing a few restful nights of sleep can’t cure. Fatigue is also common when you’re suffering from allergies or fighting an illness or infection.

Medical conditions such as autoimmune disorders and fibromyalgia can also cause ongoing tiredness, and treatments like chemotherapy are major culprits of fatigue. Fatigue can also be a symptom of long COVID, when tiredness is typically accompanied by other indications.

But you may not be aware of several surprising causes of fatigue—some that can be cured with lifestyle or diet adjustments and others that may require your doctor to assess.

Your meds make you sleepy

Drowsiness is a common side effect of many prescription medications, including some cholesterol and blood pressure medications as well as antianxiety, antidepressant and antipsychotic drugs, antihistamines, seizure meds and steroids. Diuretics can also disturb your sleep causing daytime fatigue.

Check with your physician to see if adjusting down your dose, moving morning meds to the evening or switching to an alternative medication may help you.

You’re deficient in key nutrients

A lack of iron, vitamins D, B12 and folic acid can be the cause of your fatigue. Diets high in fatty, sugary and processed foods — high in calories and low on nutrients — can also drain energy leading to drowsiness, primarily because they throw off your blood glucose and insulin levels.

Just as your vehicle can run sluggish on poor-quality gas, the same goes for your body. Food is fuel, so be sure to eat a healthy balanced diet of natural, nutrient-packed, unprocessed foods, fruit, vegetables and whole grains.

You’re dehydrated

Not drinking enough water can make your organs work in overdrive to deliver nutrients to your body, especially for oxygenating your blood. The result is dehydration which quickly causes you to feel sluggish and fatigued.

Drinking lots of water daily and eating juicy fruits like peaches, oranges and melons is the best way to deter dehydration to keep your body functioning smoothly and beat fatigue.

You may be anemic

Various types of anemia, when there are too few red cells in your blood or they lack hemoglobin that carries oxygen through your bloodstream, can cause fatigue. Beyond nutritional deficiencies like iron and B12, anemia in older adults can indicate more serious conditions.

Your physician can diagnose anemia and assess the possible causes.

You have a heart problem

Ongoing fatigue is a frequent indication of heart disease, especially as we age. In fact, fatigue is one of the most common sign of cardiac-related issues because the heart can become less efficient at pumping blood to the lungs. This can cause shortness of breath, which can exacerbate fatigue.

This is why it’s important to talk to your doctor about fatigue. This kind of fatigue can be very serious.

You’re not getting enough exercise

Although it may seem counterintuitive, not getting enough exercise can cause fatigue. Our bodies are engineered to exert a specific amount of energy, and when we don’t, it throws off our hormone balance and circadian rhythm, which can result in daytime drowsiness.

When you feel fatigued, pump up your activity level. You don’t have to go for a jog or hit the gym. Amping up your NEAT levels can help — that’s Non-Exercise Activity Thermogenesis, the calories burned doing daily activities such as shopping, cleaning, cooking, gardening or playing a musical instrument. Just get up and move.

You lack a daily routine

Having an abnormal schedule can do a number on your health and wellbeing, including increasing feelings of tiredness. Our body’s biological rhythm is heavily reliant on keeping a regular schedule. That means waking up and going to sleep at the same or similar time each day and even establishing a routine for when you run errands, do chores and take downtime.

You’re not managing stress

Our mood impacts our energy levels, and when we’re stressed, we’re in constant fight or flight mode, which increases stress hormone cortisol and decreases serotonin, the body’s feel-good hormone. Stress raises our heart rate and blood pressure which can result in extreme fatigue.

The best way to beat stress to overcome fatigue is to exercise, do yoga, meditate and pursue activities you love. Your doctor can also help you address stress.

You have a thyroid problem

Our thyroid gland produces hormones whose primary role is to regulate our metabolic system, the process of converting food and nutrients into energy for the body’s growth and maintenance. If you feel rundown and tired all the time, you may have hypothyroidism—simply put, a sluggish thyroid.

The good news: it’s treatable and diagnosed with a simple blood test.

You have a urinary tract infection (UTI)

Pain and burning when you go are the primary symptoms of a urinary tract infection. But feeling fatigued is a common forerunner symptom. It’s because your body has already started fighting the infection and is draining your energy.

Your doctor can quickly diagnose a UTI with a urine sample.

You’re addicted to your digital devices

Digital devices not only overstimulate the brain with a bombardment of information and emotional cues, they also emit blue light which messes with our body’s natural biological clock and deep REM sleep, necessary for our cells to rejuvenate.

Try taking a digital vacation. Turn off the TV and power down your computer, phone and e-reader at least an hour before bedtime — and leave them anywhere but on your nightstand to avoid temptation.

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