New research suggests that men who have the sleep disorder obstructive sleep apnea (OSA) appear to be at higher risk for depression. Remember, depression afflicts over 34 million Americans. Understanding how some sleep problems are often a symptom and a cause of depression will help anyone better understand the causes of their depression; and thus get the necessary treatment.

In this recent study of 2,000 Australian men between 35 and 83 years of age, researchers discovered those who are unusually sleepy during the day were 10% more likely to be depressed than those who were not (University of Adelaide and the Adelaide Institute for Sleep Health, 2015). After taking into account other risk factors, this relationship was tested, resulting in a strong connection between sleep apnea and depression.

To begin, these men had never been diagnosed with severe obstructive sleep apnea coming into this study, yet the researchers diagnosed 857 of them for this condition. The study found that those with the condition were a little over 2 times more likely to be depressed than those not having the sleep disorder, according to the researcher Carol Lang.

Sleep apnea is a serious sleeping disorder that has been long believed to affect depression. This recent research makes a clearer connection between the two conditions. Researchers found that some of the men suffered from both severe sleep apnea and excessive daytime sleepiness. These men were 4 times more likely to be depressed compared to those with no sleep issues. Men having both undiagnosed severe sleep apnea and excessive daytime sleepiness were at an even greater risk of depression. Their risk of depression was up to five times greater, according to this study.

The researchers evaluated all of the men twice for depression, with the second test occurring five years later. This time frame allowed the researchers to see a link between a recent diagnosis of depression and sleep apnea. This research established a clear link:  That men having sleep apnea during the study were nearly 3 times more likely to become depressed during those five years.

Although the nature of the study precludes “our drawing any conclusion to cause and effect,” Lang said, she noted that the relationship between apnea and depression was strong.

This study’s aim did not allow researchers to determine whether sleep problems increase men’s risks of depression. The reverse could be true, or even other factors could contribute to both depression and sleep disorders.

The nature of the link between sleep and depression is still not clear; however, the results do provide ENT specialists with more information to accurately diagnose treatments. The take-away from this study is that doctors should consider patients diagnosed with depression should also consider testing for obstructive sleep apnea, even if they don’t appear sleepy.