I do believe that untreated obstructive sleep apnea (OSA) is a major cause, if not the most common cause of depression. We know from numerous studies that OSA, via massive hypoxia and inflammation, causes brain biochemical and structural changes that can alter almost every aspect of your physiology and psychology.
Almost weekly, I see patients that suddenly gained significant weight after starting an antidepressant medication. We know that certain antidepressants are more likely to cause weight gain. Weight gain can aggravate obstructive sleep apnea, and obstructive sleep apnea can worsen depression. We also know that depression is linked with a higher incidence of insomnia, cardiovascular disease, and even death.
Did you gain weight after starting an antidepressant medication? If so, which one did you take?