The short answer: constant tiredness usually comes from a mix of poor sleep, stress, low mood, diet and too little movement. Sometimes there’s a medical cause, such as anemia, sleep apnea, diabetes or a thyroid problem. If you’ve felt tired for a few weeks and don’t know why, the NHS says to see your doctor.
You wake up tired. You get through the day on coffee. By 3 p.m. the words on your screen stop making sense. You go to bed early, and you wake up tired again. People tell you to get more rest, as if you hadn’t thought of that.
Let’s sort the possible causes, starting with the ones you can check yourself.
First, what kind of tired is it?
MedlinePlus separates drowsiness, which is the need to sleep, from fatigue, which is weariness or a lack of energy. Feeling worn out after poor sleep, hard work or stress is normal. Cleveland Clinic says fatigue is different because rest often doesn’t bring your energy back.
So ask yourself: if you could sleep well for three nights, would you feel better? If the honest answer is yes, look at the everyday causes first. If you’ve already rested and nothing changed, take that seriously. MedlinePlus says fatigue should be checked if rest, good food and less stress don’t ease it.
The everyday causes
The NHS and Cleveland Clinic point to many of the same things. Go through this list and be honest about your week:
- Sleep. Trouble falling asleep, irregular hours, or shift work.
- Stress and big life events. Burnout, grief, caring for someone, or a new baby.
- Low mood. Depression and anxiety can both drain your energy.
- Food. Poor diet, irregular meals, or not drinking enough.
- Too little movement. It sounds backward, but sitting still most of the day is a recognized cause.
- Alcohol. It can leave you sleeping less deeply, the NHS says.
- Hormonal changes, such as pregnancy or the menopause.
- A recent illness. The NHS names COVID-19 and glandular fever.
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Medical causes worth checking
If the everyday causes don’t explain it, look at the other clues your body is giving you. The table below draws on the NHS and MedlinePlus. It isn’t a way to diagnose yourself, but it will help you talk to your doctor.
| Possible cause | Other clues |
|---|---|
| Sleep apnea | Loud snoring, gasping or choking in your sleep, tired in the day |
| Iron deficiency anemia | Low energy, palpitations, shortness of breath, pale skin |
| Diabetes | Extreme tiredness, thirst, peeing often, weight loss |
| Underactive thyroid | Constipation, dry skin, weight gain, feeling the cold |
| Overactive thyroid | Restlessness, anxiety, muscle weakness |
| Depression | Feeling sad or down, trouble sleeping |
| ME/CFS | Extreme fatigue for at least 3 months, with thinking and memory problems |
Sources differ on timing for ME/CFS. The NHS says at least 3 months, while MedlinePlus says at least 6. It’s only diagnosed once other causes have been ruled out. Cleveland Clinic adds low vitamin D, low vitamin B12, and heart, lung and kidney disease to the list.
Could it be a medicine?
MedlinePlus lists sedatives, antidepressants, antihistamines, blood pressure medicines, sleeping pills, steroids and diuretics as possible causes of fatigue. Check over-the-counter medicines too, especially allergy tablets.
Don’t stop or change any medicine on your own. If your tiredness started around the time you began a new one, tell your doctor.
What helps: a one-week reset
This is general advice, not a promise, and it won’t fix a medical cause. But it’s the place to start, and it will show you what changes. Try it for a week:
- Keep your hours steady. Go to bed and get up at the same times each day, and avoid daytime naps. The NHS and Cleveland Clinic both say adults need 7 to 9 hours, though it varies, so aim for what leaves you feeling rested.
- Eat regularly. The NHS suggests meals and healthy snacks every 3 to 4 hours, rather than one large meal less often. A simple high-protein breakfast is an easy place to start.
- Walk for 15 minutes. The NHS says a single 15-minute walk can give you a boost. Build up slowly toward 2½ hours a week.
- Watch the timing of your caffeine. Its effects can last up to 7 hours, so avoid it in the evening if you sleep badly. Cut down slowly, the NHS says, to avoid headaches and insomnia.
- Drink some water. A glass can help if mild dehydration is part of the problem.
- Cut back on alcohol. The NHS says no more than 14 units a week, with several alcohol-free days.
- Protect your last hour. Put screens away, and keep your bedroom calm, dark and cool.
If your body also aches when you get moving, stiffness in the morning has its own causes and fixes. If you wake at night with sore legs, read about leg cramps at night.
What probably won’t fix it
More coffee. MedlinePlus says stimulants, including caffeine, aren’t effective treatments for fatigue, and that fatigue can get worse when you stop them.
Sleeping pills on your own. MedlinePlus says sedatives also tend to make fatigue worse. Talk to your doctor about what’s keeping you awake instead.
Random supplements. Cleveland Clinic lists low vitamin D and B12 as causes, so a test tells you more than a guess. MedlinePlus suggests asking your doctor whether vitamins might help.
One magic food. We found no good evidence that any single food cures tiredness, and that includes bananas. Enough protein, regular meals and plenty of plants are a better plan.
When to see a doctor
Get immediate medical care if fatigue comes with:
- Shortness of breath, or chest, arm or upper back pain
- An unusually fast or slow heartbeat, or a pounding, fluttering or irregular one
- Muscle weakness
- Headache or vision problems, especially after a head injury
- Thoughts of harming yourself or others. In the US, you can call or text 988 at any time
Contact your doctor right away if you have:
- Confusion or dizziness, or blurred vision
- Little or no urine
- Recent swelling and weight gain
Make an appointment if:
- You’ve felt tired for a few weeks and don’t know why
- Tiredness is affecting your daily life or work
- You’re also losing weight without trying, or your mood has changed
- You have a fever or regular sweats as well
- Someone has told you that you gasp, snort or choke in your sleep
The NHS says your doctor may order blood tests. MedlinePlus adds kidney, liver and thyroid tests and a urine test. Before you go, write down when the tiredness started, how you sleep, what you take, and anything else that has changed.
Your next step
Pick one thing from the one-week reset and start today. If it’s been more than a few weeks and you can’t explain it, book the appointment now, while you’re thinking about it.
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Quick questions
Why am I always tired even when I sleep enough?
Sleep length isn’t the whole story. Stress, low mood, alcohol, little exercise and poor diet can all leave you tired. So can sleep apnea, anemia, thyroid problems, diabetes and some medicines. If you’ve felt tired for a few weeks and don’t know why, see your doctor.
What tests check for tiredness?
Your doctor will ask about your life and health, and may examine you. The NHS says blood tests can check for problems such as anemia, diabetes and an overactive thyroid. MedlinePlus says tests may also look at your kidneys, liver and urine.
Does coffee help when you’re always tired?
Not as a long-term answer. MedlinePlus says stimulants, including caffeine, aren’t an effective treatment for fatigue and can make it worse when you stop. The NHS says caffeine’s effects can last up to 7 hours, so avoid it in the evening if you have trouble sleeping.
Can what I eat make me tired?
It can play a part. Both the NHS and Cleveland Clinic list poor diet as a cause of tiredness. The NHS suggests regular meals and healthy snacks every 3 to 4 hours, rather than one large meal less often.
When is tiredness an emergency?
Cleveland Clinic says to get immediate care if fatigue comes with shortness of breath, chest, arm or upper back pain, an unusually fast, slow or irregular heartbeat, muscle weakness, or thoughts of harming yourself or others.
This article is general information, not medical advice. If you’re worried about your tiredness, please talk to your doctor.
Sources
- NHS. Insomnia.
- NHS. Tiredness and fatigue. Reviewed June 2023.
- NHS. Self-help tips to fight tiredness.
- Cleveland Clinic. Fatigue.
- MedlinePlus. Fatigue.