[On the question of a primary and secondary origin of insomnia]

Approximately 30% insomnia patients have associated somatic, neurological and psychiatric conditions. Clinician has to define causality of these conditions to determine a treatment plan. Secondary insomnia can result from the symptoms of a primary condition or form an impairment of central nervous system due to neurological disorder. Some associated conditions are characterized by high coincidence with insomnia, similar triggers and crossing genotype, neurophysiological and functional findings. This association with insomnia is observed in anxiety disorders, depression, chronic pain syndromes. The paper presents a concept of comorbid insomnia disorder which proposes the existence of a common neural structure which when affected causes the symptoms of both insomnia and comorbid disorder. Comorbid disorders can also be interconnected due to the overlap of the responsible nerve centers. Positive effect of specific pharmacological, psychotherapeutical and behavioral treatment on both conditions evidences this concept.