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Why smoking and sleep apnoea can push your haemoglobin up | CION Cancer Clinics
Smoking and obstructive sleep apnoea are two of the commonest reasons for a high haemoglobin in adults. Both leave the blood short of oxygen, so the kidneys signal the marrow to make more red cells. The marrow is healthy, and the count often falls once the cause is treated. This page explains how each cause works, how doctors confirm it, and what this page cannot tell you. At CION Cancer Clinics, our haematologist reviews abnormal blood reports with you, orders only the tests that answer your question and explains each result plainly.
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Medically reviewed by Dr. Basudev PokhrelConsultant Haematologist · last reviewed September 2026, next review due September 2027
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On this page
- Can smoking or sleep apnoea really raise your haemoglobin?
- How do smoking and sleep apnoea each lower your oxygen?
- How do the two causes compare?
- What will the doctor check before blaming smoking or snoring?
- What do families often believe about snoring, smoking and blood?
- Will your haemoglobin come down if you treat the cause?
- Common questions about smoking, sleep apnoea and high haemoglobin
The short answer
Can smoking or sleep apnoea really raise your haemoglobin?
Yes. Both smoking and obstructive sleep apnoea starve the blood of oxygen, and the body answers by making more red cells. The haemoglobin on your report rises as a result, even though the bone marrow is healthy.
Why low oxygen raises the count
Your kidneys sense how much oxygen is reaching them. When it runs low, they release a hormone called erythropoietin, or EPO. EPO tells the marrow to produce extra red cells so the blood can carry more oxygen. Doctors call the result secondary polycythaemia, which simply means too many red cells with an outside cause.
Why it is worth taking seriously
Extra red cells make the blood thicker. Thicker blood flows more slowly and can raise the chance of a clot, especially in someone who also smokes, has high blood pressure or diabetes. The good news is that both causes can be changed, and the count often comes down when they are.
Reference ranges for haemoglobin differ between laboratories. A single high result is read alongside your symptoms and a repeat test, never on its own.How it happens
How do smoking and sleep apnoea each lower your oxygen?
They work in different ways, and many people, especially men in middle age, have both at once.
Smoking
Smoke carries carbon monoxide. It sticks to haemoglobin far more tightly than oxygen does, so part of every red cell is taken up and cannot carry oxygen. Cigarettes, beedis and hookah all do this.
Also raises the count by
- Damaging the lungs over years
- Shrinking the fluid part of the blood slightly
Obstructive sleep apnoea
During sleep the throat relaxes and closes, and breathing stops for a short while before you half-wake and gasp. Each pause drops the oxygen level. Repeated many times a night, the kidneys respond with more EPO.
Signs families notice
- Loud snoring with pauses and gasps
- Morning headaches and a dry mouth
- Falling asleep while sitting or driving
When both are present
Smoking inflames the throat and makes apnoea worse. Extra weight adds to both. A person who smokes, snores and is overweight often has a higher count than any single cause would explain. Treating only one of them may bring the number down less than you expect.
Long-standing lung disease such as COPD can add a third layer.Not sure whether this applies to you?
Ask an oncologistSide by side
How do the two causes compare?
Smoking
Sleep apnoea
Oxygen is displaced all day by carbon monoxide
Oxygen dips mainly at night, during sleep
Daytime finger oxygen reading can look normal
Daytime reading is usually normal too
Confirmed from your history, sometimes a carbon monoxide test
Confirmed by a sleep study, at home or in a sleep lab
Main step: stopping smoking, with support
Main step: CPAP, a mask that keeps the airway open at night
At the appointment
What will the doctor check before blaming smoking or snoring?
Repeat the count
A second blood count, taken when you are well hydrated and have not smoked that morning, shows whether the high result holds. Dehydration alone can push a result up for a day.
Ask about your nights
Expect questions about snoring, gasping, daytime sleepiness and how much you smoke. Bring your spouse or whoever shares the room, because they often notice what you cannot.
Rule out a marrow cause
An EPO level and a JAK2 blood test help separate a secondary cause from polycythaemia vera, a slow-growing blood cancer where the marrow overproduces on its own.
Test the suspected cause
A sleep study, an oxygen reading or a lung test is arranged to confirm the cause, so treatment targets the right problem instead of only the number.
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Commonly believed
What do families often believe about snoring, smoking and blood?
"Snoring is a sign of deep, good sleep."
Loud snoring with pauses and gasps is often a sign that breathing is repeatedly blocked. That sleep is broken and short of oxygen, which is why the person wakes tired and may have a rising haemoglobin.
"I only smoke a few beedis, so it cannot affect my blood."
Beedis deliver carbon monoxide and tar just as cigarettes do. There is no amount of smoking that leaves the blood untouched. Cutting down helps less than stopping completely.
"A high haemoglobin means I have extra strength."
Here the high count is the body making up for a shortage of oxygen. It does not give you more energy, and the thicker blood can raise the chance of a clot.
"A CPAP machine is only for very sick people."
CPAP is a common home treatment for sleep apnoea. Most people get used to the mask within a few weeks of trying, and many notice better sleep, fewer headaches and clearer thinking.
What helps
Will your haemoglobin come down if you treat the cause?
Often, yes. When you stop smoking or treat sleep apnoea, the oxygen signal to the kidneys eases and the marrow slows down. The count falls gradually over months rather than days, so a repeat test is spaced out rather than done the following week.
Stopping smoking
Carbon monoxide clears from the blood quickly once you stop. The red cell count takes longer to follow. Stopping is hard, and support makes it more likely to last. Ask your doctor about counselling and the medicines that help with cravings.
Treating sleep apnoea
CPAP works only on the nights you wear it, so regular use matters more than the brand of machine. Losing some weight, avoiding alcohol at night and sleeping on your side can also reduce the pauses. A small number of people are offered a mouth guard or throat surgery instead. The sleep specialist will match the option to how severe your apnoea is, and will tell you if one does not suit you.
Removing blood is not for everyone
Some people with a very thick blood are offered venesection, where a unit of blood is taken off, much like a donation. It does not suit someone whose body needs the extra red cells because of serious lung or heart disease. Taking blood off in that situation can leave them more breathless. Your treating team decides.
What this page cannot tell you
It cannot confirm that smoking or snoring is the cause of your own result. Another cause, including a marrow disorder, can sit alongside them. Only your tests and your doctor can settle that.
Did you know
A normal oxygen reading on a finger clip during the day does not rule out sleep apnoea. The oxygen drops happen while you sleep, which is why a sleep study records you overnight.
Questions we are asked
Common questions about smoking, sleep apnoea and high haemoglobin
Does a high haemoglobin from smoking mean I have blood cancer?
Usually not. Smoking is one of the most common reasons for a raised haemoglobin in adults. A marrow disorder such as polycythaemia vera is less common, and simple blood tests help tell the two apart. If your platelets or white cells are also high, mention it, because that changes the picture.
How do I know if I have sleep apnoea?
Loud snoring with pauses, gasping at night, morning headaches and feeling sleepy through the day are the usual signs. Your family often notices them first. A sleep study confirms it. Many can now be done at home with a small recording device worn overnight.
Should I get a repeat test before seeing a doctor?
A repeat count is often the first thing a doctor will ask for, so it is reasonable to arrange one. Drink normally, avoid smoking that morning and use the same laboratory if you can. Take both reports to the appointment, along with any older results.
Can I donate blood to bring my count down?
Do not do this on your own. Blood banks may turn away a donor with an unexplained high count, and removing blood can hide the real cause. If blood removal is needed, your treating team will plan it and decide how often.
Do e-cigarettes or chewing tobacco raise haemoglobin too?
Chewing tobacco does not produce smoke, so it has far less carbon monoxide, though it carries its own serious risks, including mouth cancer. The evidence on vaping and red cell counts is still limited. Tell your doctor exactly what you use.
Is a high count dangerous if I feel fine?
Many people feel well. The concern is thicker blood and a higher chance of clots over time. If you have sudden weakness on one side, slurred speech, chest pain or a painful swollen leg, call 108 or go to the nearest emergency department.
Which doctor should I see?
A physician can start the work-up. A chest or sleep specialist handles sleep apnoea and lung problems. A haematologist, a specialist in blood disorders, helps when the cause is unclear, the JAK2 test is positive, or other blood counts are also abnormal.
Can CION review my blood report?
Yes. Share your reports through the helpline and CION's haematology team can read them and suggest which tests are worth doing next. If a sleep study or lung test is needed elsewhere, the team will tell you what to ask for.
Your Haematologist
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Dr. Basudev Pokhrel reviews blood counts, transfusion needs and blood disorders, and works with the CION tumour board on blood cancers.
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Sources
- NHS — Obstructive sleep apnoea
- NHS — Polycythaemia
- National Heart, Lung, and Blood Institute — Sleep apnea
- National Health Mission — National Health Mission
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Secondary Polycythaemia: High Haemoglobin With a CauseEvery outside cause of a high red cell countRaised Counts in Dehydration and AltitudeTwo other everyday reasons for a high resultWhen a High Count Needs Marrow TestingThe signs that point beyond smoking or snoringRaised Counts and Reactive ChangesEvery guide on high blood counts in one place
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