The relationship between sleep and mood disorders is complex. Insomnia not only contributes to the development of depression but it also is a classic sign of the disorderin fact, it is one of the diagnostic hallmarks of an episode of major depression. In addition, insomnia is an independent predictor of suicide in someone who is depressed and of relapse in a person who has been successfully treated for depression.
In a National Institute of Mental Health study of nearly 8,000 people, those who had insomnia when the study began and at the one-year mark were far more likely to develop a new episode of major depression than those without insomnia. In contrast, those whose insomnia had resolved by the one-year mark had a much lower risk of depression.
Insomnia also is deeply intertwined with anxiety disorders. Panic disorder, post-traumatic stress disorder (PTSD), generalized anxiety disorder and social phobia are all associated with sleep disruption and insomnia.
In a European study, anxiety was related to insomnia in 47 percent of people who had a history of a mood disorder. Persistent trouble falling asleep at night, or waking up too early, is neither normal nor inevitable with age.