Dr Amir Khan has warned anyone who wears a fitness watch at night that it may pick up on a health issue that warrants booking a doctor's appointment. In the latest episode of his No Appointment Necessary podcast, the NHS GP and ITV doctor discussed what to do if a fitness watch detects oxygen levels (SPO2) dropping below 90% during the night, warning this may indicate sleep apnoea.
What the readings could mean
The medical condition causes a temporary obstruction of the airway, leading to poor sleep quality. Dr Khan said that while the accuracy of individual watches may vary, such readings should be taken as a serious potential sign of health issues that can strain the heart and lungs, potentially causing other issues like high blood pressure. He recommends undergoing a professional sleep study for a definitive diagnosis.
Many fitness watches and smartwatches measure blood oxygen levels, known as SpO2 or Pulse Ox, using light sensors on the back that emit red and green light into the skin and measure how much light bounces back from the blood. These gadgets track fitness and wellness but are not medical devices and should not be relied upon to diagnose health issues. Factors like movement, cold skin, tattoos, or a loose fit can lead to inaccurate readings.
Dr Khan's advice
Reading out a viewer's question, presenter Cherry Healey asked Dr Khan: "How serious should we take the night measurements of our fitness watches?" He replied: "I can't speak to how accurate your individual watches are, but they're probably a good enough indication. They might not be 100% accurate, but they're probably picking up something that's dropping."
He warned: "If your oxygen levels are dropping through the night, it usually means you've got something called sleep apnoea. You stop breathing altogether for a very short period of time and then you wake up." He explained that with sleep apnoea, there is complete obstruction of the upper airway briefly, then waking enough to open the airway again, causing oxygen levels to drop. This can lead to waking up not feeling refreshed.
He added: "But also that chronic dropping of oxygen through the night can lead to increased pressure on your heart. It can lead to high blood pressure and long-term issues as well. So if you are getting those readings on your watch, I would first of all ask your partner, 'Am I making this noise?' But if it's not the case, your doctor can refer you for something called sleep studies, where they will monitor your oxygen while you sleep, and they'll give you a definitive answer."
Potential health problems
The NHS states: "Sleep apnoea is when your breathing stops and starts while you sleep. The most common type is called obstructive sleep apnoea (OSA). Sleep apnoea needs to be treated because it can lead to more serious problems." Without treatment, sleep apnoea can lead to high blood pressure, a higher chance of having a stroke, type 2 diabetes, heart disease, depression or mood changes, a higher chance of a serious accident caused by tiredness, and difficulty concentrating at work or school. It may also be difficult for a partner and strain relationships.
Drivers with confirmed sleep apnoea with excessive sleepiness must not drive until symptoms are under control, and may need to tell the DVLA. Symptoms include breathing stopping and starting, gasping, snorting or choking noises, waking up a lot, loud snoring, and daytime tiredness, difficulty concentrating, mood swings, or headaches on waking.
The NHS says sleep apnoea can sometimes be treated with lifestyle changes like losing weight, giving up smoking, and reducing alcohol intake, but many people need a CPAP machine, provided free on the NHS. Other treatments include a mandibular advancement device, surgery to help breathing, mouth and facial exercises, or hypoglossal nerve stimulation.
