Short answer: Low energy in men usually comes from one of a short list of causes: poor or disrupted sleep (including sleep apnea), low testosterone, thyroid problems, low iron or ferritin, low vitamin B12, depression or chronic stress, blood sugar problems such as diabetes or insulin resistance, medication side effects, and alcohol. If tiredness lasts two weeks or more despite rest and better habits, Mayo Clinic advises booking an appointment, and some symptoms alongside fatigue need emergency care. A doctor can sort the likely causes with a history, an exam and a few targeted blood tests.
Key Takeaways
- Fatigue is common: it is reported by 5% to 10% of patients in primary care, according to a 2023 review in American Family Physician.[1]
- Most low energy in men traces back to sleep, mood, lifestyle, hormones, blood and metabolic issues, or medicines. The checklist table below links each cause to a full guide.
- Chest pain, shortness of breath, a fast or irregular heartbeat, feeling faint, severe pain, unusual bleeding or a severe headache with fatigue means emergency care, not a wait-and-see plan.[2]
- Useful first tests usually include a blood count, thyroid function, blood sugar, kidney and liver tests, and, depending on symptoms, iron studies, B12 and a morning testosterone level.[3][4][5]
- Labs ordered without clear reasons rarely change treatment, so your symptoms and history should guide which tests you ask about.[1]
- No supplement replaces a proper workup. Fix the obvious habits, track your symptoms, and see a clinician if the tiredness does not lift.
Tired or Fatigued? What Low Energy in Men Actually Means
Everyone gets tired after a short night or a hard week. That kind of tiredness improves when you sleep, eat and rest. Fatigue is different: it is an ongoing lack of physical or mental energy that rest does not fully repair. Cleveland Clinic notes that fatigue lasting six months or more is considered chronic.[4]
Two features help separate normal tiredness from something worth investigating:
- Duration. Mayo Clinic suggests calling for an appointment if fatigue persists for two or more weeks despite resting, reducing stress, eating well and drinking enough fluids.[2]
- Company. Fatigue that arrives with other symptoms (weight change, mood change, loud snoring, feeling cold, more thirst, low sex drive) points toward specific causes. The NHS lists tiredness with symptoms such as weight loss or mood changes as a reason to see a GP.[3]
It also helps to be honest about the odds. In the American Family Physician review, only 27% of young adults presenting with first-time fatigue in primary care were diagnosed with a condition that explained it, and in another study only 8% had a clear condition-based diagnosis a year later.[1] In other words, many cases come down to sleep, stress, mood and daily habits. That is not a reason to skip the doctor: the visit is how you rule out causes that need real treatment.
The Causes of Fatigue in Men: A Checklist
Use this table as a map, not a diagnosis. Read the “clues” column and note which rows sound like you, then bring that list to your appointment. Each cause links to a deeper guide on this site.
| Cause | Clues that often come with it | What a doctor may check | Deep dive |
|---|---|---|---|
| Obstructive sleep apnea | Loud snoring, gasping or choking at night, unrefreshing sleep, morning headaches, dozing off during the day | Sleep history, partner report, referral for a sleep study | Sleep apnea and testosterone |
| Low testosterone | Low sex drive, lower endurance, loss of muscle, low mood | Morning testosterone, usually on two separate samples | Signs of low testosterone |
| Thyroid problems | Underactive: feeling cold, dry skin, constipation, weight gain. Overactive: weight loss, racing heart, feeling hot | Thyroid function tests | Hypothyroidism symptoms in men |
| Low iron or ferritin (with or without anemia) | Shortness of breath on exertion, pale skin, poor exercise tolerance | Blood count, iron studies including ferritin | Low ferritin in men |
| Vitamin B12 deficiency | Tingling or numbness, memory or balance problems, a sore tongue | Vitamin B12 level, blood count | B12 deficiency symptoms |
| Depression, anxiety or chronic stress | Low mood, loss of interest, irritability, poor sleep, trouble concentrating | Mood screening questions, discussion of stressors | Men’s mental health |
| Diabetes or insulin resistance | Thirst, frequent urination, energy crashes after meals, a growing waistline | Fasting glucose or HbA1c, sometimes insulin for HOMA-IR | HOMA-IR test |
| Medication side effects | Fatigue that started or worsened after a new drug or a dose change | Full medication and supplement review | Sleeping pill side effects |
| Alcohol | Regular drinking, especially in the evening, poor sleep quality, low next-day energy | Honest drinking history, liver tests | How much alcohol is too much |
Apart from low testosterone (covered by Cleveland Clinic’s hypogonadism page[6]), each of these causes appears on the fatigue cause lists of Cleveland Clinic, the NHS and MedlinePlus.[3][4][5] The clue column describes typical patterns only; your doctor will interpret them in context. Many men have more than one cause at once: for example, sleep apnea, a growing waistline and low testosterone often travel together, and so do alcohol, poor sleep and low mood.
Other causes worth knowing
The nine rows above cover the most common medical and lifestyle drivers, but they are not the whole list. MedlinePlus and Cleveland Clinic also name infections (including COVID-19, mononucleosis and hepatitis), heart failure and other heart or lung disease, kidney disease, liver disease, autoimmune conditions, persistent pain, cancer, fibromyalgia and ME/CFS (chronic fatigue syndrome).[4][5] Lifestyle causes include a sedentary routine, poor diet, burnout, jet lag and shift work.[4] This is exactly why persistent fatigue deserves a clinician’s eyes rather than a guess.
Medications that commonly cause tiredness
Cleveland Clinic lists several drug classes that can cause fatigue: benzodiazepines, sedative-hypnotics, antipsychotics, anxiolytics, opioids, anticonvulsants and beta-blockers, plus over-the-counter antihistamines.[4] MedlinePlus adds sedatives and antidepressants.[5] If your energy dropped after starting one of these, do not stop it on your own. Ask the prescriber whether the timing, dose or drug can be adjusted. Related reading: opioids and testosterone and prednisone side effects in men.
Red Flags: When Fatigue Needs a Doctor Now
Some combinations should not wait for a routine appointment.
Get emergency help (call 911)
Mayo Clinic advises emergency care if fatigue comes with any of the following:[2]
- Chest pain
- Shortness of breath
- Irregular or fast heartbeat
- Feeling that you might pass out
- Severe stomach, pelvic or back pain
- Unusual bleeding, including bleeding from the rectum or vomiting blood
- Severe headache
If fatigue is tied to a mental health problem and you have thoughts of harming yourself, call 911 right away. In the U.S. you can also call or text 988.[2] MedlinePlus also lists confusion or dizziness, blurred vision, little or no urine output, and recent swelling with weight gain as reasons to contact a provider right away.[5]
Book an appointment soon
- Fatigue lasting two weeks or more despite self-care.[2]
- Unexplained fatigue with fever, unintentional weight loss or regular sweats.[5]
- Constipation, dry skin, weight gain or trouble tolerating cold (possible underactive thyroid).[5]
- A partner telling you that you gasp, snort or choke in your sleep.[3]
- Tiredness that is affecting work, driving or daily life.[3]
- Feeling sad or depressed, or ongoing insomnia.[5]
Which Blood Tests to Ask About
There is no single “fatigue test.” The American Family Physician review says the first lab workup should be guided by your history, exam and the common causes of fatigue, and notes that labs ordered without specific reasons may change treatment in only about 5% of patients.[1] The goal is to match tests to your clues.
| Test | What it looks for | When it makes sense |
|---|---|---|
| Complete blood count (CBC) | Anemia and some infections | Most fatigue workups[3][5] |
| Thyroid function tests | Underactive or overactive thyroid | Most fatigue workups, especially with weight, temperature or bowel changes[3][5] |
| Fasting glucose or HbA1c | Diabetes and prediabetes | Thirst, frequent urination, weight gain, family history[3][5] |
| Kidney and liver function tests | Kidney or liver disease, alcohol-related liver strain | Common part of a basic panel[5] |
| Iron studies with ferritin | Iron deficiency, which can exist without anemia | Poor exercise tolerance, shortness of breath on exertion, possible blood loss[5] |
| Vitamin B12 | B12 deficiency | Numbness or tingling, memory or balance changes, other unexplained fatigue[4] |
| Morning total testosterone | Low testosterone (hypogonadism) | Low sex drive, lower endurance, loss of muscle; drawn in the morning, usually twice[6] |
| Urinalysis | Kidney problems, sugar in the urine, infection | Part of a broader workup[5] |
A few practical tips. Testosterone is normally drawn in the morning when levels are highest, and Cleveland Clinic notes that illness can temporarily lower it, so mention it if you are sick on test day.[6] Cleveland Clinic considers adult levels below 300 ng/dL low, and notes that levels can decline by about 1% per year starting in the late 30s.[6] For timing details, see the best time to check testosterone levels, and for context on results, normal testosterone levels by age. If you suspect sleep apnea, the key test is a sleep study, not a blood test.
What You Can Do This Week (While You Wait for Answers)
- Protect sleep. Cleveland Clinic advises adults to aim for seven to nine hours a night.[4] Keep a fixed wake time and move screens and alcohol away from bedtime. Our sleep routine guide lays out a simple plan.
- Keep a two-week fatigue log. Note bedtime, wake time, snoring reports, caffeine, alcohol, meals, exercise, mood and when the energy dips hit. This is the single most useful thing to bring to the doctor.
- List every medicine and supplement. Include over-the-counter sleep aids, antihistamines and herbal products.
- Cut back on alcohol. MedlinePlus lists regular alcohol or drug use as a cause of fatigue.[5]
- Eat regular meals and drink enough fluids. Mayo Clinic’s self-care advice includes eating well and drinking plenty of fluids.[2]
- Move a little every day. A sedentary lifestyle is itself a cause of fatigue.[4] Start with walks and build up gradually. The one exception: if you suspect ME/CFS, where the AFP review notes exercise therapy is no longer recommended, talk to your doctor before pushing harder.[1]
For the habit side of the problem, read our guides on how to get more energy and foods that give you energy.
Where Supplements Fit (and Where They Do Not)
Supplements cannot diagnose low iron, low thyroid, sleep apnea or diabetes, and taking one can delay the visit that would. If a blood test shows a true deficiency, your clinician will advise on the right form and dose. If you already take herbal products, list them for your doctor, since some can interact with prescription medicines.
Ultra Bann, from DL Bioproducts, is a natural male vitality supplement with seven botanicals listed with their amounts on the label: Thai Butea superba, Panax ginseng, Cynomorium songaricum, black ginger (Kaempferia parviflora), tongkat ali, epimedium and reishi, taken as one capsule every two days. It is not a substitute for a medical workup of fatigue. You can review the full ingredient label or see the product, which includes free US shipping and a 60-day money-back guarantee on a first order.
Frequently Asked Questions
Why am I always tired even when I sleep 8 hours?
Time in bed is not the same as good sleep. Obstructive sleep apnea, alcohol in the evening and some medicines can fragment sleep so you wake unrefreshed. Medical causes such as anemia, low thyroid, diabetes and depression can also cause fatigue no matter how long you sleep.[3][5] If this lasts two weeks or more, see a doctor.[2]
Can low testosterone cause fatigue in men?
Low testosterone is associated with lower endurance, low sex drive and low mood, and Cleveland Clinic notes that treatment of confirmed low testosterone can improve energy levels.[6] It is diagnosed with morning blood tests, usually on two separate samples, not by symptoms alone. Fatigue alone is not enough to assume low T, because thyroid, iron, sleep and mood problems can look similar.
What blood tests should a man get for fatigue?
Common starting points are a complete blood count, thyroid function tests, blood sugar (fasting glucose or HbA1c), and kidney and liver tests.[3][5] Depending on your symptoms, your doctor may add iron studies with ferritin, vitamin B12 and a morning testosterone level. Testing should follow your history rather than a fixed panel.[1]
When is fatigue an emergency?
Seek emergency care if fatigue comes with chest pain, shortness of breath, a fast or irregular heartbeat, feeling faint, severe pain, unusual bleeding or a severe headache, or if you have thoughts of harming yourself (call or text 988 in the U.S.).[2]
How long is too long to feel tired?
Mayo Clinic suggests booking an appointment when fatigue lasts two or more weeks despite rest and self-care.[2] Fatigue lasting six months or longer is considered chronic and deserves a structured evaluation.[1][4]
References
- Latimer KM, Gunther A, Kopec M. Fatigue in Adults: Evaluation and Management. American Family Physician. 2023;108(1):58-69. aafp.org
- Mayo Clinic. Fatigue: When to see a doctor. mayoclinic.org
- NHS. Tiredness and fatigue. nhs.uk
- Cleveland Clinic. Fatigue: Causes and Treatment. clevelandclinic.org
- MedlinePlus Medical Encyclopedia. Fatigue. U.S. National Library of Medicine. medlineplus.gov
- Cleveland Clinic. Low Testosterone (Male Hypogonadism). clevelandclinic.org
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease. This article is for information only and is not medical advice.
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