If you feel tired all the time, even after a full night in bed, you're not imagining it, and it's not necessarily "just stress" or "just getting older." Persistent fatigue is one of the most common reasons men see a doctor, and it often has a cause that can be found and treated.
The short answer: the most common medical causes of fatigue in men include poor sleep (including sleep apnea), low iron or anemia, thyroid problems, high blood sugar, low testosterone, low vitamin levels, medication side effects, and depression or chronic stress. Several can overlap. A careful history and the right blood tests can usually narrow it down.
When is tiredness worth checking?
Everyone has tired days. It's worth looking into when fatigue:
- lasts more than a few weeks;
- doesn't improve with rest or a few good nights of sleep;
- comes with other changes, such as weight gain or loss, low sex drive, brain fog, low mood or shortness of breath; or
- is affecting your work, training or relationships.
1. Poor sleep and sleep apnea
The most common cause of daytime tiredness is not getting enough good sleep. That can mean too few hours, irregular sleep times, or sleep that's broken up without you noticing. Obstructive sleep apnea, where the airway repeatedly narrows or closes during sleep, is common in men and easy to miss. Loud snoring, a partner noticing pauses in your breathing, morning headaches and dozing off during the day are all clues. We cover this in signs of sleep apnea in men.
2. Low iron and anemia
Anemia means your blood carries less oxygen than it should. It can make you tired, short of breath with exercise, and pale. In men, anemia or low iron always deserves a look for the cause, which can include blood loss from the gut. A complete blood count and ferritin (your iron stores) are simple tests that check for it.
3. Thyroid problems
An underactive thyroid slows your metabolism. Typical signs include fatigue, feeling cold, weight gain, constipation, dry skin and low mood. A TSH test, sometimes with free T4, checks thyroid function.
4. High blood sugar
Prediabetes and diabetes can cause fatigue, especially energy crashes after meals, along with thirst and frequent urination. Many men with high blood sugar feel nothing at all, which is why testing matters. A1c and fasting glucose are the standard checks. Read more in prediabetes: what it is and how it's reversed.
5. Low testosterone
Low testosterone can cause low energy and motivation, along with low sex drive, loss of muscle and gains in body fat. But fatigue alone is not enough to diagnose it, and testosterone levels change through the day. A diagnosis needs symptoms and low levels on at least two separate early-morning tests. See why one blood test isn't enough.
6. Low vitamin D and B12
Low vitamin D is common, even in sunny places like Florida, since many of us spend most of the day indoors. Low vitamin B12 can cause fatigue, numbness or tingling and memory problems, and is more likely in people who take certain stomach-acid or diabetes medications or eat little animal food. Both are easy to measure.
7. Medications and alcohol
Many common medications can cause tiredness, including some blood pressure medications, antihistamines, sleep aids and pain medications. Alcohol, even a few drinks in the evening, breaks up sleep in the second half of the night. If you're tired, it's worth reviewing everything you take and drink.
8. Mood, stress and burnout
Depression doesn't always look like sadness. In men, it often shows up as fatigue, irritability, poor sleep and loss of interest. Long-term stress can do the same. These are real, treatable medical issues, not character flaws, and they deserve the same attention as a lab result.
What tests help find the cause?
A good starting point usually includes a complete blood count, ferritin, a metabolic panel (kidney and liver function), A1c and fasting glucose, TSH, vitamin D and B12, and morning testosterone when symptoms suggest it. You can see all the tests your doctor can order on our lab work page.
Labs are only half of it. The other half is your history: how you sleep, what you eat and drink, how you train, what you take, and how your mood has been. That's why a doctor who takes the time to ask matters.
The bottom line
Persistent fatigue has a cause more often than not, and many causes are simple to find and treat. Don't settle for "you're just getting older."
At Ora, one doctor looks at your sleep, labs, hormones and history together to find what's behind your fatigue. Learn more about our care for energy and fatigue, or see how it works.
