Sleep apnoea and high blood pressure: the overlooked connection
30 to 40 per cent of people with high blood pressure have obstructive sleep apnoea. In treatment-resistant high blood pressure the proportion is even higher – and the diagnosis is often missing for years.
When blood pressure does not come down despite medication and lifestyle changes, the usual response is to adjust the dose. But one of the most common causes lies elsewhere: in sleep.
According to the German Hypertension League (Deutsche Hochdruckliga), 30 to 40 per cent of people with high blood pressure have obstructive sleep apnoea. Conversely, around 50 per cent of people with sleep apnoea have raised blood pressure. In treatment-resistant hypertension – that is, when three medications do not bring the reading into the target range – the connection is particularly common.
What happens in obstructive sleep apnoea
During sleep, the muscles of the throat relax. In some people the airway collapses so far that air can no longer get through. Breathing stops – typically for ten seconds or longer, in severe cases several hundred times a night.
The oxygen level in the blood falls. The body responds with an alarm reaction: the sympathetic nervous system ramps up, pulse and blood pressure rise, the person briefly wakes – usually without noticing – and breathing starts again. Then the cycle begins anew.
That pulse and blood pressure do not move in step during this – and what palpitations have to do with it – is explained on Palpitations, pulse and blood pressure.
These arousal reactions are the crucial point. They prevent blood pressure from falling at night.
Why the missing night-time dip matters
In healthy people, blood pressure falls by 10 to 20 per cent during sleep compared with the daytime value. This dip is a recovery phase for the heart and blood vessels. If it does not happen, this is called a non-dipper profile.
In sleep apnoea this is precisely the rule: every arousal reaction drives the pressure up, and the night-time average stays high. Why this carries more cardiovascular weight than a raised daytime reading is explained in Why your blood pressure at night matters more than during the day.
The practical catch: home measurement in the morning and evening does not pick this up. You are measuring the wrong time window. It only becomes visible with 24-hour ambulatory blood pressure monitoring.
Waking at night can be captured – the night-time profile cannot
To avoid any misunderstanding: for the night-time pressure profile, there is no way around 24-hour ambulatory blood pressure monitoring. That remains the case, and no home device replaces it.
But this article also covers a second situation: waking up short of breath, a racing heart in the middle of the night. By the time a cuff is in place, such an episode is over. This is exactly where a blood pressure event recorder works differently from a blood pressure monitor.
Conventional blood pressure monitor
ResultTwo numbers
Night-time pressure profileNot captured – that is what 24-hour monitoring is for
Waking with a racing heartOver by the time the cuff is on
TechnologySingle oscillometric measurement
BPER blood pressure event recorder
ResultThe curve of pressure and pulse, beat by beat
Night-time pressure profileNot captured either – 24-hour monitoring is still needed for that
Waking with a racing heartRecorded in 60 seconds
TechnologyBeat-to-beat recording
Class IIa medical device · no subscription · 30-day right of return
Signs that point to sleep apnoea
- Loud, irregular snoring with observed pauses in breathing – a partner often notices this before the person affected
- Waking up short of breath or with a choking sensation
- Marked daytime sleepiness despite sufficient sleep, nodding off while reading or at the wheel
- Morning headaches and a dry mouth
- Problems with concentration and memory
- Needing to urinate at night
- Morning readings clearly higher than evening readings in your blood pressure log
Not every snorer has sleep apnoea, and not all sleep apnoea comes with loud snoring – in women it more often shows itself in non-specific ways, such as exhaustion or disturbed sleep. A combination of several of these points and blood pressure that is hard to control is the reason to have it investigated.
How the diagnosis works
The first step is a consultation with your GP, often with a standardised questionnaire. If sleep apnoea is suspected, this is followed by home polygraphy: a device for use at home that records airflow, snoring sounds, oxygen saturation, pulse and body position over one night.
If the results are abnormal, polysomnography in a sleep laboratory follows, with additional measurement of brain waves, eye movements and muscle activity. This gives the apnoea-hypopnoea index – the number of breathing pauses per hour – which determines the severity.
In parallel, 24-hour ambulatory blood pressure monitoring is useful to capture the night-time pressure profile. Together, the two examinations give a picture that neither provides on its own.
What treatment can achieve
The standard treatment for moderate to severe obstructive sleep apnoea is continuous positive airway pressure (CPAP) at night. It keeps the airway open and prevents the arousal reactions.
It has an effect on blood pressure: in studies, blood pressure falls with consistent CPAP use, with the effect being more pronounced in people with treatment-resistant hypertension and with good nightly wearing time. CPAP does not replace blood pressure medication – it removes a cause that medication does not address.
Depending on the findings, a mandibular advancement splint, positional therapy or treatment by an ear, nose and throat specialist may also be options. Losing weight and avoiding alcohol in the evening help with both conditions at once – alcohol increases the relaxation of the throat muscles.
When you should seek medical advice
- If your blood pressure does not reach the target range despite several medications
- If your morning readings are regularly clearly higher than your evening readings
- If pauses in breathing have been observed during your sleep
- If you have marked daytime sleepiness, especially microsleeps at the wheel – this is urgent
- If you have morning headaches together with loud snoring
In case of sudden severe headache, chest pain, speech or visual disturbances or one-sided paralysis: call the emergency services on 112 immediately.
For the night-time profile, 24-hour ambulatory blood pressure monitoring remains the method of choice. For the individual episode – waking with a racing heart – the BPER blood pressure event recorder records pressure and pulse over 60 seconds, beat by beat.
How to describe your symptoms so your doctor can actually work with them
Five steps for your next doctor’s appointment – plus a printable template for noting down your observations.
This is how it usually sounds
“I felt strange again last night. A kind of stumble, and it gave me a fright.”
“Let’s keep an eye on it.”
The guide shows you how to describe it instead and which questions to ask. What is usually missing are the numbers from exactly those two minutes – and those are what the BPER records, beat by beat.
Frequently asked questions
How common is sleep apnoea in high blood pressure?
According to the German Hypertension League (Deutsche Hochdruckliga), 30 to 40 per cent of people with high blood pressure have obstructive sleep apnoea. In treatment-resistant hypertension the proportion is even higher.
Why does sleep apnoea raise blood pressure?
Every pause in breathing lowers the oxygen level in the blood. The body responds with an arousal reaction in which the sympathetic nervous system ramps up and pulse and blood pressure rise. As a result, the night-time dip in blood pressure does not happen.
Can sleep apnoea be seen in blood pressure readings at home?
Not directly. Home measurement covers morning and evening, not the night. One indication can be morning readings that are clearly higher than evening readings. Only 24-hour ambulatory blood pressure monitoring gives certainty.
How is sleep apnoea diagnosed?
First through a consultation with a doctor and usually a questionnaire, then through home polygraphy. If the results are abnormal, polysomnography in a sleep laboratory follows.
Does CPAP therapy lower blood pressure?
In studies, blood pressure falls with consistent CPAP use, especially in treatment-resistant hypertension and with good nightly wearing time. It does not replace blood pressure medication.
Does a blood pressure event recorder replace 24-hour monitoring?
No. For the night-time pressure profile, 24-hour ambulatory blood pressure monitoring is the appropriate method. An event recorder instead records a short curve of about 60 seconds – beat-to-beat – and is intended to capture individual episodes, such as waking at night with a racing heart.
What can I do if I wake up at night with a racing heart?
Raise the episodes with your doctor, especially if pauses in breathing have been observed or your blood pressure is hard to control. Anything that documents the moment is helpful: time, duration, accompanying symptoms. A blood pressure event recorder can record the curve of pressure and pulse over about 60 seconds. Chest pain, shortness of breath or fainting are not a reason for documentation but an emergency – call the emergency services on 112.
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Sources
- Deutsche Hochdruckliga e. V. DHL: Bluthochdruck und Schlaf
- AWMF/DGSM: S3-Leitlinie Schlafbezogene Atmungsstörungen (Registernummer 063-001)
- Nationale VersorgungsLeitlinie Hypertonie (2023)
- European Society of Cardiology: 2024 ESC Guidelines for the management of elevated blood pressure and hypertension
This article is for general information only and does not replace a medical diagnosis or treatment. If you have symptoms or questions about your treatment, please consult your doctor.