How Major Depressive Disorder (MDD) Can Cause Sleep Apnea in obese Veterans

Veterans often suffer from both obesity and Major Depressive Disorder (MDD)—and these two conditions can work together to cause obstructive sleep apnea (OSA). While obesity is a well-known contributor to sleep apnea, recent medical and legal evidence shows that MDD is also a significant and independent cause, especially in veterans.

Understanding Sleep Apnea

The VA defines sleep apnea as a disorder that occurs when breathing repeatedly stops or becomes very shallow during sleep. According to Dorland’s Medical Dictionary, OSA specifically involves the collapse or obstruction of the airway during REM sleep, when most muscles—including those in the throat and tongue—are paralyzed.

This collapse is not just a mechanical issue. Most people with sleep apnea breathe normally while awake. The problem happens only during sleep, especially during REM (dream) sleep, when the tongue and airway muscles are relaxed. In overweight individuals, even a slightly narrowed airway due to fat deposits can cause the tongue to block airflow during REM.

Why MDD Matters

Major Depressive Disorder directly affects REM sleep. Veterans with MDD often report severe nightmares, fragmented sleep, and abnormal REM cycles. These sleep disturbances are known to weaken muscle tone in the airway, making it more likely for the tongue to fall back and cause blockage during sleep.

This is critical because both mechanical narrowing (from obesity) and loss of muscle control (from REM sleep and MDD) are required for OSA to develop. So, if a veteran has both obesity and MDD, the MDD is not just a contributing factor—it’s a necessary one. That makes it a “substantial factor” in causing the sleep apnea, which under VA regulations (38 CFR § 3.310) qualifies the veteran for secondary service connection.

Legal Support for This Claim

The U.S. Court of Appeals has clarified that if more than one factor causes a condition, a service-connected disability still qualifies if it’s a “substantial factor” in causing the harm. In the case of sleep apnea, both obesity and MDD can be causes, and if the MDD plays a key role, the veteran is entitled to benefits.

This standard was confirmed in Shyface v. Secretary of Health & Human Services, where the court ruled:

“An action is considered to be a proximate cause of harm if it is a substantial factor in bringing about the harm, and the harm would not have occurred but for that action.”

What the Science Shows

Several large studies back up this connection between MDD and OSA in veterans:

• A VA study of over 4 million veterans found that more than 50% of those with sleep apnea also had mood disorders, including depression, anxiety, and PTSD.
• The association between MDD and sleep apnea in this study was statistically significant—so strong that the results could not have occurred by chance.
• A separate VA study looked at obese veterans with and without MDD. The researchers found that obese veterans with MDD were far more likely to have sleep apnea than those without MDD—even when their body weight (BMI) was the same.
• Another study found that MDD increases the risk of OSA by up to five times, even in people without obesity.

These studies confirm that MDD is more than a background condition—it is often the trigger that transforms a narrow airway into a fully obstructed one during REM sleep.

What About PTSD and TBI?

The same research also shows high rates of OSA in veterans with PTSD and mild traumatic brain injury (TBI). In one study of active-duty soldiers, more than 60% had sleep apnea, and many had multiple overlapping conditions like insomnia, depression, and PTSD. Veterans with both insomnia and OSA were found to have the highest rates of mood disorders, confirming a strong link.

The Veteran Population Is Different

The Board of Veterans’ Appeals (BVA) has sometimes wrongly compared veterans to the general population. But this is misleading. In the civilian population, only about 12.5% of obese people have sleep apnea. In contrast, over 50% of veterans with MDD or PTSD have it. That’s 4–5 times higher.

Comparing veterans to the general public ignores the unique physical and psychological toll of military service, and underestimates the true impact of MDD on sleep apnea in this population.

Bottom Line: MDD Is a Proven Cause of Sleep Apnea in Veterans

Veterans who are obese and suffer from MDD (or PTSD, or TBI) are significantly more likely to develop sleep apnea—not just because of weight, but because their service-connected mental health conditions disrupt REM sleep, paralyze throat muscles, and lead to airway collapse.

For this reason, the VA should recognize sleep apnea as a secondary condition to MDD under 38 CFR § 3.310, and veterans should receive the benefits they deserve.