I was excited to see an article in today's NY Times about the role of treating insomnia in the greater context of depression. This is a topic that has long been recognized in the sleep field, but one that hasn't been given much attention in the mainstream media (or even psychiatry in general).
Those in the medical field have typically been taught that sleep disruption (such as insomnia) is usually a symptom of another disorder. For example, if someone has major depressive disorder and also reports insomnia, their therapist usually decides to focus treatment upon the depression, with the thought that as the depression remits, so too will the sleep problem. The reality is that insomnia is more often a comorbidity, not simply a symptom of another disorder. We typically have been treating only a piece of the puzzle, addressing daytime depression symptoms and ignoring nighttime factors that can influence our mood and overall health.
Recent studies aimed directly at treating insomnia using Cognitive Behavior Therapy for Insomnia (CBT-I; see here for more info) in depressed patients have shown that depression severity can lessen even without directly treating the depression. Even better, targeting the depression and insomnia separately but as part of a comprehensive treatment overall (often relying on non-pharmacological treatments, too) can be greatly beneficial for the patient with depression and insomnia.