Do you think it's possible that sleep disorders are at the root of most common mental disorders?

I'm talking about depression and schizophrenia mainly. It's been doented that people who are deprived of sleep for long periods of time will show symptoms of psychosis, and people with depression tend to sleep in longer and feel fewer symptoms when they are well-rested. Could the conscious behavior of the mentally ill be symptoms of prolonged improper sleep, as if only a part of their brain had chronic insomnia and was the source of the malfunction?