What Is Mild Sleep Apnea?
The severity of someone’s sleep apnea is defined by the average number of breathing events that occur per hour of sleep, often measured by the apnea-hypopnea index (AHI). A person with mild sleep apnea experiences an average of five to 14.9 breathing events per hour. Moderate and severe sleep apnea are characterized by a higher number of breathing events. The following categories are used:
- Normal breathing: 0 to 4.9 events per hour
- Mild sleep apnea: 5 to 14.9 events per hour
- Moderate sleep apnea: 15 to 29.9 events per hour
- Severe sleep apnea: 30 and higher events per hour
The score is calculated by adding up all the breathing events during the entire sleep period, then dividing that number by the number of hours slept. The definition of a “breathing event” can change depending on whether you count just apneas and hypopneas, or also milder events called respiratory-effort related arousals (RERAs). The following definitions are used:
- Apnea: An apnea is a complete or near-complete pause in breathing during sleep that lasts for at least 10 seconds and restricts airflow by at least 90%.
- Hypopnea: A hypopnea occurs when airflow during sleep is restricted by at least 30% for 10 seconds or longer, causing a 3% or 4% drop in the blood oxygen saturation and/or an arousal from sleep. Insurers may use different definitions of hypopnea.
- Respiratory-effort related arousal (RERA): This brief awakening from sleep is caused by increased resistance in the upper airway that makes breathing more difficult with a less than 30% reduction of airflow from baseline. Most insurers do not recognize this in determining sleep apnea severity.
When an in-lab test includes apneas, hypopneas, and RERAs, it’s termed the respiratory disturbance index (RDI), which is more sensitive to mild cases of sleep apnea. Sleep studies may also report the oxygen desaturation index (ODI), which measures the number of times per hour that blood oxygen levels decrease during sleep.
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Mild Sleep Apnea Symptoms
Symptoms of mild sleep apnea are similar to symptoms of moderate to severe sleep apnea, but they may be less noticeable:
- Loud, frequent snoring
- Waking up gasping or choking
- Noticeable pauses in breathing
- Daytime sleepiness or fatigue
- Morning headaches
- Dry mouth
- Bruxism
- Nocturia (frequent nighttime urination)
- Night sweats
- Nocturnal heartburn
- Heart palpitations
- Insomnia
- Changes in mood, thinking, or behavior
Someone with mild sleep apnea may experience daytime sleepiness only during monotonous or sedentary activities. People may also get used to being sleepy, to the extent that they don’t realize it’s not normal to feel that way.
Causes of Mild Sleep Apnea
Mild sleep apnea has the same causes as moderate or severe sleep apnea, but it’s important to differentiate between the two types of sleep apnea: obstructive sleep apnea and central sleep apnea.
Central sleep apnea (CSA) results when the brainstem fails to send proper signals to the muscles that control breathing during sleep, and it’s usually caused by an underlying medical condition, such as heart failure, stroke, kidney failure, brainstem injury, or opioid use.
In obstructive sleep apnea, lapses in breathing are due to physical blockage of the airway. Some potential factors for OSA include:
- Obesity
- Neck circumference larger than 16 inches in women and 17 inches in men
- Large tonsils
- Anatomical features that narrow the airway or nasal passages
- Older age
- Menopause
Drinking alcohol before bed, taking sedative medications, and sleeping on your back may trigger breathing events, as these all relax the muscles and tissues in the airway.
Diagnosing Mild Sleep Apnea
The best way to diagnose mild sleep apnea is with a laboratory sleep study, which records information about breathing, blood oxygen levels, brainwaves, and other metrics during sleep. While at-home sleep apnea tests can more often diagnose moderate to severe OSA, they may not be sensitive enough to detect mild cases.
To obtain a formal diagnosis of sleep apnea, a person must have at least five breathing events per hour of sleep. And for mild sleep apnea, specifically, a person must have an AHI between five and 14.9.
Although mild sleep apnea is currently defined by the number of breathing events per hour, some experts argue that this doesn’t give the full picture. For example, when considering the risk of certain heart problems, there’s evidence to suggest that nighttime blood oxygen levels may be more significant than the number of breathing events.
Additionally, having a higher percentage of events during rapid eye movement (REM) sleep may be worse for health. It’s common for women with sleep apnea to have more events in REM sleep and be diagnosed with milder forms of sleep apnea. Similarly, someone with long periods of shallow breathing may be diagnosed with mild sleep apnea, even if these periods last much longer than a typical apnea.
Experts say it might be more useful to consider multiple factors, such as effects on sleep, nervous system activity, and changes in blood pressure, when determining whether sleep apnea requires treatment.
Mild Sleep Apnea Treatment
Mild sleep apnea is most effectively treated with CPAP therapy or an oral appliance. People with central sleep apnea should also treat the medical condition that’s causing the apnea, such as heart failure.
- Continuous positive airway pressure (CPAP) therapy:CPAP therapy keeps the airway open during sleep by blowing a gentle stream of pressurized air into the nose or the nose and mouth. This is the most commonly prescribed therapy, and it works well for mild, moderate, and severe sleep apnea.
- Oral appliances: Oral appliances keep the airway open by pulling the lower jaw and the tongue forward. These devices are effective for mild to moderate OSA but less effective for severe OSA.
- Myofunctional therapy: Therapy exercises for the muscles in the upper airway might help improve symptoms of mild OSA, especially when combined with a tongue stimulator like eXciteOSA, but more research is needed.
- Lifestyle changes: Working toward a healthy weight, getting regular exercise, and avoiding alcohol and sedatives can all help with sleep apnea.
- Treating nasal congestion: Clearing up nasal congestion and allergies with medicine or nasal sprays can help promote nasal breathing, which in turn improves OSA.
- Practicing good sleep hygiene: Sleeping soundly tends to lower the amount of breathing interruptions during sleep, and this may be particularly true for people with mild OSA. Also, switching from back sleeping to side sleeping can also be helpful.
Note: You shouldn’t use mouth tape unless you’ve already talked to your doctor, as there isn’t enough evidence on whether this effectively treats sleep apnea and, in fact, may be dangerous for people with untreated sleep apnea or who have significant difficulties breathing through the nose. Mouth tape should never be used by someone who is at risk of vomiting, as this may lead to aspiration and death.
Frequently Asked Questions
Is mild sleep apnea dangerous?
Mild sleep apnea has fewer health consequences than moderate and severe sleep apnea, but it still carries some risks. In particular, mild sleep apnea appears to contribute to high blood pressure (including systemic arterial hypertension) and possibly atrial fibrillation. For some people, mild sleep apnea also causes daytime sleepiness, which may be dangerous in traffic or sensitive work situations.
Does mild sleep apnea need to be treated?
Mild OSA should be treated if it’s causing symptoms or if you have a co-existing disorder like high blood pressure. Experts also recommend treating mild OSA if you have a job that requires being alert for safety reasons, as is the case for pilots, air traffic controllers, bus and truck drivers, locomotive engineers, or doctors and nurses. Sleep apnea treatments have been shown to have positive effects on blood pressure and quality of life.
Can mild sleep apnea go away?
Sleep apnea is generally considered a lifelong disorder, but when it’s mild, it may go away, depending on the underlying cause. For example, mild sleep apnea due to obesity may go away if you lose weight. Some people only get sleep apnea symptoms on nights when they drink alcohol or if they’re very tired.
Mild sleep apnea won’t necessarily progress to moderate or severe sleep apnea, but it does often worsen as you age or if you gain weight, especially if left untreated.
Do you need a CPAP for mild sleep apnea?
CPAP therapy for mild sleep apnea is effective, but it’s not the only treatment option. Mild sleep apnea also responds well to special mouthguards that hold the tongue and jaw in a better position for breathing.
Depending on the cause of your sleep apnea, you may also find your symptoms improve with lifestyle changes like losing weight, treating seasonal allergies, sleeping on your side, or cutting out alcohol before bed.
Can mild sleep apnea cause high blood pressure?
Although it’s not as strongly implicated in most health markers, mild OSA does increase the risk of high blood pressure, especially for younger people. This holds true even if you don’t have symptoms like daytime tiredness.
Does mild sleep apnea make you tired?
Some people experience unrefreshing sleep and daytime sleepiness due to mild sleep apnea, while others have no symptoms and might not even notice they have sleep apnea at all. It’s fairly common for people not to realize they have daytime sleepiness until they start sleep apnea treatment and suddenly find they have more energy.
How common is mild sleep apnea?
It’s estimated that almost one billion people worldwide have OSA, and approximately half of these cases are mild. However, many of these people haven’t been diagnosed and might not be aware they have sleep apnea. OSA diagnoses are rising, partly due to better diagnostic methods but also because of rising obesity rates.
