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A Deadly Duo: The Dangers of High Blood Pressure and Sleep Apnoea
It’s no secret that there’s a link between obstructive sleep apnoea (OSA) and high blood pressure, or hypertension. But what you might not know is just how dangerous that link is. Sleep apnoea and high blood pressure are a deadly combination. Both can lead to serious complications, such as stroke and heart attack.
How Do You Know You’re At Risk?
If you’re an OSA sufferer, when you sleep the soft tissue in the back of your throat, your uvula (that’s the dangly thing), your tongue and the pharyngeal wall (that’s a muscle group that wraps around the top of your throat so you can swallow), all combine over time to sag and block your airway.
This is called hypopnea and it’s the beginning stage of a gradual or partial collapse. Hypopnea presents as snoring and eventually graduates to a full blockage known as sleep apnoea where all those muscles collapse completely.
The issue with being hypertensive (having high blood pressure) is that when your muscles collapse, your blood oxygen drops and if your blood oxygen drops below 90% it’s a bad sign.
In fact, if you were in a hospital it'd be a red alert. Your natural blood oxygen or saturation levels as they call it in the medical profession should be at around 96% or 97%.
Here at Sleep Clinic Services, we've treated patients with blood saturation levels of only 63%. It's amazing they even survived. Thankfully, since having treatment their blood pressure has improved dramatically.
You see when blood oxygen or blood saturation drops your heart has to work even harder to pump to circulate oxygen around your body, especially to your brain.
When your blood saturation doesn't increase that's when your brain sends a signal to your nervous system to wake you up briefly to resume breathing and bring your blood oxygen levels back up. That brief awakening you experience is called a micro-arousal. You wake up, take a deep breath or gasp, relax again and fall straight back to sleep. In fact, it’s so brief that you won’t even realise it’s happening. Not only that, but it can happen hundreds of times in one night.
What a stressful ordeal on your body, which is why the link to blood pressure comes as no surprise.
Hypertension and sleep apnoea have been studied in combination for years. And recent research published in The Journal of Clinical Endocrinology & Metabolism found that untreated sleep apnoea raises blood pressure.
"This is one of the first studies to show real-time effects of sleep apnea on metabolism during the night," says Jonathan Jun, M.D., assistant professor of medicine at the Johns Hopkins University School of Medicine and the paper's senior author.
Jun and colleagues drew blood samples from 31 patients with moderate to severe OSA and a history of regular CPAP use for two nights. The researchers drew samples every 20 minutes starting at 9 pm and until 6:40 am. Every participant spent one night in the lab with CPAP or after CPAP had been stopped for two nights, in random order, separated by one to four weeks.
Jun and colleagues found that CPAP withdrawal caused recurrence of OSA associated with sleep disruption, elevated heart rate, and reduced blood oxygen. CPAP withdrawal also increased levels of free fatty acids, glucose, cortisol and blood pressure during sleep.
The evidence is clear, getting treatment for snoring and sleep apnoea is so important. Not only to reduce your risk of stroke and heart attack but to prevent high blood pressure in the first place. Unless someone notices you having a micro-arousal during the night, detecting sleep apnoea can be really difficult. If you’re suffering from any of the signs of OSA or you have trouble sleeping you can take our free sleep self-assessment questionnaire.
Swati Chopra, Aman Rathore, Haris Younas, Luu V. Pham, Chenjuan Gu, Aleksandra Beselman, Il-Young Kim, Robert R. Wolfe, Jamie Perin, Vsevolod Y. Polotsky, Jonathan C. Jun. Obstructive Sleep Apnea Dynamically Increases Nocturnal Plasma Free Fatty Acids, Glucose, and Cortisol during Sleep. The Journal of Clinical Endocrinology & Metabolism, 2017.