Why am I always tired? 8 common causes of persistent fatigue

Do you feel tired all the time — even after a full night’s sleep?

You’re not alone. Many people feel this way, and it can be frustrating, confusing, and sometimes even scary.

The important thing to know: constant fatigue is not something you should ignore. Your body is often trying to tell you something.

“Fatigue is more than just feeling sleepy. It’s a constant lack of energy that doesn’t get better with rest,” said Mufius Shaikh, MD, family medicine physician at Endeavor Health.

Dr. Shaikh breaks down the most common reasons this happens:

1. Your sleep habits or a sleep disorder. You might be in bed for 7-8 hours, but still wake up tired. That’s because sleep quality matters just as much as sleep time. Some things that can affect your sleep include: scrolling on your phone late at night, an irregular sleep schedule and caffeine or alcohol before bed. Sometimes, there’s an actual sleep disorder, like sleep apnea, where breathing briefly stops during sleep. Clues to watch for include:
   • Loud snoring
   • Waking up gasping
   • Morning headaches
   • Feeling unrefreshed no matter how long you sleep

2. Stress, anxiety or depression are draining your energy. Stress doesn’t just affect your mind — it affects your body too. When you’re constantly stressed, your body stays in “high alert” mode. Over time, this can leave you feeling mentally exhausted, physically drained and unable to relax or recharge.

   Additionally, many people expect mental health issues to feel emotional — but often, they feel physical. Fatigue can be one of the main symptoms. You might notice:

   • Low energy or motivation
   • Trouble concentrating
   • Poor sleep
   • Feeling “slowed down” or overwhelmed

   This is very common — and very treatable.

3. Low vitamins or anemia. Your body needs certain nutrients to make energy. If levels are low, you may feel constantly tired. Common causes include low iron (anemia), low vitamin B12, and low vitamin D. You might notice:

   • Weakness
   • Shortness of breath
   • Feeling lightheaded

   The good news: this is easy to check with basic lab tests.

4. Thyroid problems or blood sugar issues. Your hormones act like your body’s “energy regulators.” If they’re off, your energy can drop. Examples include:

   • Hypothyroidism (low thyroid): slow, sluggish feeling
   • Diabetes: energy ups and downs

   These conditions are common and manageable once diagnosed.

5. Ongoing medical conditions. Some health problems naturally make your body work harder, which leads to fatigue. This includes conditions affecting the heart, lungs, kidneys and immune system. Autoimmune and inflammatory conditions can also cause persistent tiredness.

6. Your daily habits or medications. Sometimes the cause is simpler than expected. Everyday factors that drain energy include:

   • Not drinking enough water
   • Poor diet
   • Too little (or too much) exercise
   • Alcohol use

   Also, some medications can make you feel tired, including: allergy medications, sleep aids, blood pressure medications, and some antidepressants.

7. Fatigue after an illness (like COVID or flu). Have you ever felt like you never fully got your energy back after being sick? That’s real. Some people develop long-lasting fatigue after infections, including COVID-19 or mono. You may notice:

   • “Brain fog” (trouble focusing)
   • Low energy that lingers for weeks or months
   • Feeling worse after even small amounts of activity

   When this lasts a long time and affects daily life, it may be part of chronic fatigue syndrome.

When should you be concerned?

It’s normal to feel tired sometimes. But you should get checked if your fatigue:

• Lasts more than a few weeks
• Doesn’t improve with rest
• Is getting worse
• Is affecting your daily life

Seek care sooner if you also have chest pain, shortness of breath, unexplained weight loss and/or new neurological symptoms.

What happens at a doctor visit?

Most of the time, figuring out fatigue does not require a huge workup. Your doctor will focus on:

• Sleep habits
• Stress and mental health
• Diet and lifestyle
• Medications
• Basic labs if needed

The goal is to find the root cause and not just treat the symptoms.

Finding relief from persistent fatigue

If you’re always tired, there’s usually a reason — and often more than one. The good news is that many causes of fatigue are treatable and reversible. You don’t have to just “push through it.” Getting answers is the first step to getting your energy back.

If you’ve been dealing with ongoing fatigue, schedule an evaluation with your doctor. They can help review your symptoms, identify the cause, and guide you toward better energy and overall health.

Schedule an appointment with Dr. Shaikh today.