Along with irritability, another way sleep apnea affects your mood is depression. Depression is a condition that causes sadness and a loss of interest in normal activities. Having sleep apnea greatly increases the risk of depression. Some sufferers of sleep apnea describe almost a different personality due to the condition. For many, it is hard to attribute sleep apnea as the cause of the depression. In some cases, the sleep apnea occurs before the depression. Other times, the depression will come first. This often confuses people because they aren’t sure if the two are linked. However, you may want to consider if sleep apnea is the underlying cause of your depression.