Why am I always tired when my blood tests are normal?

By Aamir Malik, PhD, Professor of Neuroengineering at Brno University of Technology

Published 21 October 2026 · Updated 21 October 2026

This guide shares wellness information to use alongside your doctor, never instead of one.

Why don’t my tests show anything?

A blood test looks for a short list of known problems. Tiredness often starts in places a blood test never looks: how you sleep, how much you move, what you eat, and how much time you spend with people who matter to you.

The book has a name for this: being “fine on paper”. Your last check-up was normal, and yet something is quietly slipping that a standard check-up never measures.

That doesn’t mean your tiredness is imagined. It means the cause may be in your week, not in your blood.

Did my tests check the right things?

Before you change your habits, ask your doctor what was checked. The book suggests starting with:

• Iron, including ferritin (your iron stores). Low iron can drain energy before it shows up as anemia. Test before you take iron, because too much iron causes tiredness too.
• Vitamin B12.
• Thyroid.
• Blood sugar.

And two questions a blood test can’t answer:

• Could it be sleep apnea? Ask if you snore, or wake up unrefreshed however long you slept.
• Could a medicine be the cause? Some medicines flatten energy.

What drains energy when the tests are normal?

Fix the Floor looks at five pillars: sleep, food, exercise, friends and family, and daily habits. Each one can drain you.

Sleep. Too little sleep, or sleep that doesn’t refresh you, is the most direct cause of low energy there is. Start with the same wake time every day and bright light soon after you wake.

Exercise. This is the surprise. When you are tired, rest feels like the answer. For ordinary tiredness it is usually the opposite. Across dozens of trials in adults living with long-term conditions, becoming more active reliably lowered fatigue. Cardio and strength training both help.

Food. Your body needs fuel and raw materials: enough protein, enough water, and vitamins and minerals such as iron, B12, folate, thiamin, vitamin C and magnesium. Sugary drinks and refined carbs push your blood sugar up and then let it drop, and the drop can leave you flat later in the day.

Friends and family. Loneliness drains energy in the most literal sense. In a study of nearly 12,000 older adults, loneliness predicted who would develop fatigue later. Burnout, too, is at heart emotional exhaustion.

Daily habits. Caffeine helps for an hour and hides the sleep debt underneath. Taken late, it steals from the very night that would restore you. Morning daylight and breaking up long sitting both help.

Should I rest more or move more?

For ordinary tiredness, move more, and start small. As the book puts it: “The energy you’re waiting to feel before you move is, for most people, made by moving.”

There is one important exception. If even modest effort reliably makes you much worse a day or two later (a crash of exhaustion, brain fog and aching that can last for days), don’t push through. That pattern is called post-exertional malaise. It is the hallmark of ME/CFS (myalgic encephalomyelitis, also called chronic fatigue syndrome) and of long COVID. Here the approach is pacing, living within your energy limits, with care from a clinician who knows these conditions. The ordinary soreness of starting to train is not this.

What to try first

Work on several of these at once. The pillars pull on each other: a short night makes you hungrier for sugar and less likely to move, so one fix on its own often disappoints.

1. Go through the tests above with your doctor.
2. Keep the same wake time every day, weekends included, and get daylight soon after waking.
3. Start moving. Start absurdly small if you must, but start, and build up. Expect some soreness in the first week.
4. Eat proper meals with enough protein and water, and cut back on sugary drinks and refined snacks.
5. Have your caffeine early in the day.
6. Get in touch with one person this week.

Give it two to three weeks before you judge it. A drifting body clock takes that long to reset, and the first week of exercise is the hardest.

Talk to your doctor if

• your tiredness is new, persistent or unexplained
• it comes with weight loss you didn’t intend, breathlessness, fever, or a racing or pounding heart
• you crash a day or two after effort
• you snore loudly, gasp or choke at night, or someone has seen you stop breathing
• you ever fall asleep without meaning to, mid-conversation or at the wheel: that is urgent

Tiredness is how many serious problems first show themselves, including anemia, thyroid trouble, sleep apnea, diabetes, depression, a medicine’s side effect, and heart or kidney trouble. Each of those has a real answer once it is found. Use the steps above alongside that medical look, never instead of it.

From the book

Aamir Malik knows this tiredness from the inside. In the book’s introduction he describes years of it: “I’d wake feeling as though I’d spent the night negotiating with someone, and drag that fog into the day.”

Fix the Floor comes with a home self-assessment, about fifty minutes, that shows you which of your five pillars to fix first.

Fix the Floor: Your health breaks at its weakest link. Find yours. Fix it.

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