What Causes Sleep Apnea? Risk Factors & Why It Happens

Sleep apnea affects over 30 million Americans, but what actually causes it? Understanding the root causes— from anatomical factors to lifestyle choices—is key to prevention, treatment, and knowing your risk.

The Two Main Types of Sleep Apnea

Sleep apnea has different causes depending on the type:

Obstructive Sleep Apnea (OSA) - 84% of Cases

Your throat muscles relax during sleep, causing soft tissue to collapse and physically block your airway. This is by far the most common type.

Central Sleep Apnea - 15% of Cases

Your brain fails to send proper signals to breathing muscles. The airway isn't blocked—your body simply "forgets" to breathe. Often associated with heart failure, stroke, or neurological conditions.

Complex Sleep Apnea - 1% of Cases

A combination of both obstructive and central types. Sometimes develops when treating OSA with CPAP unmasks underlying central apnea.

What Causes Obstructive Sleep Apnea?

OSA results from a combination of anatomical factors, lifestyle choices, and medical conditions that narrow or collapse your upper airway during sleep.

Anatomical Causes (What You're Born With)

1. Narrow Airway

Some people naturally have a smaller throat or airway. This can be inherited or due to:

• Small jaw (micrognathia or retrognathia): Recessed or undersized jaw pushes tongue backward
• Large tongue (macroglossia): Takes up more space in throat
• Large tonsils or adenoids: Especially common cause in children
• Long soft palate or uvula: More tissue to vibrate and collapse
• Deviated septum: Blocks nasal breathing, forcing mouth breathing

2. Neck Circumference

High risk: Neck circumference greater than 17 inches (men) or 16 inches (women).

A thicker neck has more soft tissue around the airway that can collapse during sleep. This is why neck size is one of the strongest predictors of sleep apnea.

3. Facial Structure

Certain facial features increase risk:

• Recessed chin
• High, narrow palate
• Crowded upper airway
• Small nasal passages

Lifestyle and Modifiable Causes

1. Excess Weight (The #1 Modifiable Risk Factor)

70% of people with sleep apnea are overweight or obese.

How weight causes sleep apnea:

• Fat deposits around neck: Compress and narrow the airway
• Abdominal fat: Reduces lung volume, affecting breathing mechanics
• Inflammation: Obesity causes systemic inflammation that affects airway tissues
• Hormonal changes: Affect muscle tone and breathing control

Good news: Losing just 10% of body weight can reduce sleep apnea severity by 26% or more. Learn more about how weight loss affects sleep apnea.

2. Alcohol Consumption

Alcohol relaxes throat muscles far more than normal sleep does. Even people who don't normally have sleep apnea can experience it after drinking.

Effect: Drinking within 4 hours of bedtime significantly worsens sleep apnea. The later you drink, the worse the effect.

3. Smoking

Smokers are 3x more likely to have sleep apnea than non-smokers.

Why:

• Increases inflammation and fluid retention in upper airway
• Damages airway tissues
• Disrupts sleep architecture

Good news: Quitting smoking reduces sleep apnea risk. The airway inflammation decreases over time.

4. Sedatives and Sleep Medications

Benzodiazepines, opioids, and some sleep aids relax throat muscles and suppress breathing reflexes, worsening sleep apnea.

Important: If you have sleep apnea, tell your doctor before taking any sedating medications.

5. Sleep Position

Sleeping on your back (supine position) allows gravity to pull your tongue and soft palate backward, narrowing the airway.

Positional OSA: Some people only have sleep apnea when sleeping on their back. Side sleeping can eliminate or significantly reduce apneas in these cases.

Medical Conditions That Cause Sleep Apnea

1. Nasal Congestion

Chronic allergies, deviated septum, or nasal polyps force mouth breathing, which increases sleep apnea risk.

Why: Nasal breathing creates negative pressure that helps keep the airway open. Mouth breathing doesn't provide this benefit.

2. Hypothyroidism

Underactive thyroid increases sleep apnea risk through:

• Weight gain
• Fluid retention in airway tissues
• Reduced muscle tone

3. Polycystic Ovary Syndrome (PCOS)

Women with PCOS have significantly higher sleep apnea rates due to:

• Hormonal imbalances
• Insulin resistance
• Weight gain

4. Type 2 Diabetes

Bidirectional relationship: diabetes increases sleep apnea risk, and sleep apnea worsens diabetes control.

5. High Blood Pressure

50% of people with hypertension have sleep apnea. The relationship is bidirectional—each condition worsens the other.

Age and Gender Factors

Age

Sleep apnea risk increases significantly after age 40. Why:

• Loss of muscle tone in throat
• Weight gain with age
• Accumulation of fat deposits
• Changes in sleep architecture

Gender

Men are 2-3x more likely to have sleep apnea than women—until menopause.

Why men have higher risk:

• Longer, narrower airways
• Fat distribution (more neck/upper body fat)
• Testosterone may affect airway muscle tone
• Higher rates of smoking and alcohol use

Why women's risk increases after menopause:

• Loss of progesterone's protective effect on airway muscles
• Weight gain and fat redistribution
• Hormonal changes affecting breathing control

Learn more about sleep apnea in women and why it's often missed.

Genetic Factors

Family history matters: If a parent or sibling has sleep apnea, your risk is 2-4x higher.

What's inherited:

• Facial and jaw structure
• Airway anatomy
• Body fat distribution patterns
• Tendency toward obesity
• Breathing control mechanisms

What Causes Central Sleep Apnea?

Central sleep apnea (CSA) is less common and has different causes than OSA:

1. Heart Failure

40-50% of people with heart failure have central sleep apnea. The heart's inability to pump effectively disrupts breathing control.

2. Stroke or Brainstem Damage

Damage to the brain's breathing control centers can cause central apnea.

3. High Altitude

Sleeping at high elevations (above 8,000 feet) can trigger central sleep apnea due to lower oxygen levels.

4. Opioid Medications

Chronic opioid use suppresses the brain's breathing drive, causing central apneas.

5. Kidney Failure

Disrupts breathing control through metabolic imbalances.

Can Sleep Apnea Be Prevented?

While you can't change anatomical factors or genetics, you can reduce risk by addressing modifiable causes:

Prevention Strategies

• Maintain healthy weight: Most important preventable factor
• Avoid alcohol before bed: Especially within 4 hours of sleep
• Quit smoking: Reduces airway inflammation
• Sleep on your side: Prevents gravity-induced airway collapse
• Treat nasal congestion: Address allergies, use nasal strips
• Exercise regularly: Helps with weight control and improves muscle tone
• Manage medical conditions: Control diabetes, hypertension, hypothyroidism

When Anatomy Is the Cause

If your sleep apnea is primarily due to anatomical factors (small jaw, large tongue, narrow airway), lifestyle changes alone may not be enough. Treatment options include:

• CPAP therapy: Most effective for any cause
• Oral appliances: Reposition jaw to open airway
• Surgery: For specific anatomical issues (enlarged tonsils, deviated septum, jaw abnormalities)

Understanding Your Personal Risk

You're at higher risk if you have:

• BMI over 30
• Neck circumference over 17" (men) or 16" (women)
• Age over 40
• Family history of sleep apnea
• Male gender (or postmenopausal woman)
• Chronic nasal congestion
• Small jaw or recessed chin
• Large tonsils
• Regular alcohol consumption
• Smoking
• Medical conditions (diabetes, hypertension, heart disease)

If you have 3+ risk factors, consider getting tested. Learn more about early warning signs of sleep apnea.

The Bottom Line

Sleep apnea is caused by a combination of factors—some you can control, others you can't. Anatomical factors like jaw structure and airway size are inherited, but lifestyle factors like weight, alcohol, and smoking are modifiable. Understanding your personal risk factors helps you take preventive action and seek treatment early. Even if anatomy is the primary cause, effective treatments like CPAP can eliminate sleep apnea regardless of the underlying cause.

Medical Disclaimer: This article is for informational purposes only. If you suspect sleep apnea, consult a healthcare provider for proper diagnosis. Learn more about sleep apnea symptoms and treatment.