Central sleep apnea is less common than obstructive sleep apnea (OSA). It is thought to affect around 0.9% of the over 40 population in the US. Nonetheless, it can be just as dangerous as OSA and as such warrants timely diagnosis and treatment, which is why knowing how to tell the difference is important. In this article, we’ll look at the difference between the two, where they vary in terms of causes, symptoms, diagnosis and finally how to treat them. First let’s take a closer a look at what central sleep apnea actually is.

Central sleep apnea v obstructive sleep apnea: What’s the difference?

Central sleep apnea occurs when the brain fails to send the right signals to the muscles associated with breathing during the night. This brain-muscle communication breakdown most often occurs when the message to breathe is not transmitted for intervals of over 10 seconds. The brain and body then do not receive sufficient oxygen.

This contrasts with obstructive sleep apnea which occurs when the soft tissue in the back of the throat relaxes causing partial or total obstruction of the upper airway for recurrent episodes during the night. Here the apnea can be considered a ‘body’ issue and not a ‘brain’ one, as is the case with central sleep apnea.

If untreated both types of sleep apnea can have serious long-term health ramifications, which is why correct diagnosis and treatment plans are essential.

Central sleep apnea: Causes and risk factors

As central sleep apnea is essentially the break-down in communication between the brain and the muscles responsible for breathing, it is often caused by several conditions that compromise the brain-stem which links the brain to the spinal cord. Some of the most common causes of central sleep apnea are:

• The use of certain pain medication: For example opioids such as morphine, codeine and oxycodone which can cause intermittent interruptions in breathing and/or irregular breathing patterns.
• Chronic kidney disease: an estimated 10% of patients suffering from chronic kidney disease have central sleep apnea.
• Congestive heart failure: Adults with congestive heart failure are at a higher risk for a type of central sleep apnea associated with Cheynes-Stokes breathing- in which respiration is characterized by an alternation between periods of apnea (absence of breathing) and rapid breathing.
• Neurological conditions: Alzheimer’s, Parkinson’s, ALS, Lou Gehrig’s
• Stroke: Generally speaking both CSA and OSA are not uncommon after a stroke, with central sleep apnea being considered a consequence of medullary or bilateral hemispheric strokes in particular.
• Damage to the brain stem: Due to injury or infection (encephalitis).
• High altitude: Periodic breathing can occur in places above 8,000ft.

It is important to note here that, just as with obstructive sleep apnea, both age and gender have an impact. Men are more likely to suffer from central sleep apnea than women with one study stating that the difference 7.8% v. 0.3% may be linked to hormones.

Similarly age plays an important role, with the over 65s being at greater risk for all types of sleep apnea, although in these cases central sleep apnea is likely linked to the medical conditions listed above.

Due to being linked to the soft tissue in the upper airway, obstructive sleep apnea has its own distinct causes and risk factors including obesity, smoking, asthma, nasal congestion, alcohol and certain sedatives etc. that it doesn’t share with central sleep apnea.

Central sleep apnea v obstructive sleep apnea: Symptoms

When it comes to symptoms, obstructive and central sleep apnea are largely similar Common symptoms of both types of apnea include:

• Excessive day-time tiredness
• Mood changes
• Difficulty concentrating
• Lack of memory
• Reports of abnormal breathing from partners.
• Waking up short of breath
• Day-time headaches

Symptoms distinct to obstructive sleep apnea include:

• Waking up with a sore throat
• Waking up with a dry mouth
• Loud snoring (snoring in patients with CSA is less remarkable)
• Mouth breathing through the night
• Waking up with the need to urinate

Patients suffering from central sleep apnea often complain of suffering from insomnia, notably here, the difficulty to fall back asleep once they’ve woken up in the middle of the night. Seeing as the two types of sleep apnea share many common symptoms, how then are they diagnosed?

Central sleep apnea v obstructive sleep apnea: Diagnosis

Upon suspicion of a sleep breathing disorder, a doctor will refer the patient to a sleep specialist for a sleep study. As we’ve previously discussed, this sleep study will either take place in a sleep center or (if possible) in the patient’s home. In most cases the sleep study will last a night, although multiple nights is preferable. Several key bio-signals will be monitored by a polysomnograph (PSG) or an at-home sleep test (HST). These bio-signals can include:

• Respiratory activity
• Breathing patterns
• Chest movement through the night (or across several nights).
• Blood oxygen level
• Heart rate,
• Movement and position changes and
• Snoring events and intensity
• And in the case of Sunrise, mandibular jaw movements

This data will confirm the presence of apnea (defined as pauses in breathing/ diminished respiration of over 10 seconds) and help the sleep doctor start to build up a picture of what type of apnea the patient is suffering from. By combining this nocturnal data with a patient’s medical history (use of certain medication, other health conditions, lifestyle), a sleep doctor will likely be able to diagnose a patient, recommend further tests if necessary and create the appropriate treatment plan.

Central sleep apnea v obstructive sleep apnea: Treatment

If untreated, sleep apnea can have serious long-term consequences for the patient’s health. However, there is good news! Effective treatment exists for both central sleep apnea and obstructive sleep apnea. But the question is, given the differences between the two types of sleep apnea, how does treatment vary?

Obstructive sleep apnea treatment options include:

• CPAP (Continuous Positive Airway Pressure): The most common and effective treatment is the CPAP, a breathing mask that supplies the wearer with a constant level of pressure to keep the airway open throughout the night.
• Surgery: In certain cases surgery such as tonsillar hyperplasia tonsillectomy is recommended.
• Mandibular advancement devices: Sometimes known as apnea mouth guards or mandibli splints, these devices push the lower jaw slightly forward, which tightens the soft tissue at the back of the throat preventing it from blocking the upper airway.
• Nasal EPAP: This ‘band-aid’-like device is essentially a small valve attached externally to the sleeper’s nostrils. It works by creating a slight resistance when the sleeper breathes out, this creates a light pressure and helps keep the airway open.
• Lifestyle changes: Weight loss, physical activity, avoiding alcohol and smoking as well as sedatives and relaxants.

Central sleep apnea treatment options include:

• Implantable devices: The FDA recently approved a pace-maker-device that artificially stimulates the phrenic nerve (located in the chest) to send a message to the diaphragm which controls breathing.
• BPAP (Bilevel Positive Airway Pressure) devices: Unlike the CPAP recommended for use in cases of obstructive sleep apnea that maintains a constant level of pressure, the BPAP is recommended for use in cases of central sleep apnea. These devices have different settings of pressure for inhalation and exhalation which enables the sleeper to maintain a normal breathing rhythm throughout the night.
• Changes in medication: If the central sleep apnea is linked to the use of certain medications such as opioids, the healthcare provider will put in place a plan to taper off the use of these drugs.

As we’ve seen there are several key differences in obstructive sleep apnea and the rarer but equally serious central sleep apnea. Detecting and diagnosing any sleep apnea is a crucial first step in finding the right treatment. Sunrise is a lightweight device that detects sleep apnea. The sleeper sticks the Sunrise deviceon their chin and allows the measurement of their sleep across multiple nights. By measuring the movement of the mandibular jaw among other key metrics and then analysing these measurements with AI, Sunrise gives thehealthcare provider the information needed for a correct diagnosis.