Always tired? How to find the cause of low energy

Your fatigue pattern is a clue

When you feel tired can point toward why. Waking unrefreshed suggests a sleep problem such as apnea, alcohol-disrupted sleep or night sweats. An afternoon crash after a heavy lunch can relate to meal composition, short sleep and normal body rhythms. Feeling worse the day after exertion rather than during it is a pattern worth mentioning specifically, especially after a viral illness. Constant tiredness with no pattern can reflect anemia, thyroid disease, depression or a medication.

Keeping a simple diary for one to two weeks, noting sleep, energy levels through the day, meals, caffeine, alcohol and activity, gives your clinician far more to work with than a general sense of being tired. A pattern does not replace testing, but it helps choose the right tests.

The usual suspects in midlife

MedlinePlus lists the most common causes of fatigue as anemia and iron deficiency, depression or grief, persistent pain, sleep disorders such as insomnia and sleep apnea, thyroid problems and alcohol or drug use. In midlife, add perimenopause, low testosterone in some men, B12 deficiency in people on metformin or acid-reducing drugs, and insulin resistance.

Iron deserves a special mention. Ferritin, a marker of iron stores, often falls before anemia shows up, so a normal blood count does not rule out low iron. Heavy periods in perimenopause are a frequent reason.

Medications that cause tiredness

Many common medicines can cause fatigue, including some antidepressants, antihistamines, blood pressure drugs such as beta blockers, sleeping pills, sedatives, steroids and diuretics. A medication you have taken for years can start causing tiredness when another drug is added or as your body changes with age. Over-the-counter products, especially sleep aids and allergy medicines, count too.

Do not stop a prescribed medication to test whether it is the cause. Talk with the prescriber, who may be able to adjust the dose, timing or choice of drug.

Red flags that need prompt care

Some kinds of fatigue should not wait for a routine telehealth visit.

• Confusion, dizziness or blurred vision: seek care right away
• Little or no urine, or sudden swelling and weight gain: seek care right away
• Thoughts of harming yourself: call 911 or 988 immediately
• Fatigue with unexplained weight loss, fever or drenching night sweats: see a clinician soon
• Fatigue that is getting steadily worse week by week
• Falling asleep unintentionally during the day, especially while driving

Fatigue after a virus

Tiredness after an infection such as COVID-19 or flu often improves over weeks, though it can take longer. If you feel markedly worse after physical or mental effort, pushing through with hard exercise can backfire; pacing, gradually increasing activity within your limits, is usually safer. Blood tests are still worthwhile to rule out anemia, thyroid problems and other treatable causes. There is no good evidence that NAD+ or vitamin infusions treat post-viral fatigue.

What a fatigue workup at HealifyMD looks like

Your clinician starts with questions: when the tiredness began, how it affects your day, how you sleep, what you drink, what has changed in your life and every medication and supplement you take. Expect questions about mood too, because depression and anxiety are common, treatable causes of exhaustion that no blood test will show.

A baseline lab panel usually follows. Depending on your history, it may cover a blood count, ferritin, B12, thyroid function, blood sugar markers, kidney and liver function, vitamin D and, for some people, sex hormones. If something in your history points toward sleep apnea, your clinician may suggest a sleep evaluation before anything else. The goal is to find a cause you can treat, not just to add an energy supplement on top.

How long until you feel better

Recovery depends on the cause. Energy may improve within a few weeks of treating a B12 or vitamin D deficiency, while rebuilding iron stores and correcting thyroid levels can take a couple of months. Treating sleep apnea often helps quickly once therapy is used consistently. If treatment corrects the lab number but you feel only slightly better, there may be more than one cause, and your clinician will look again.