Insomnia ICD-10-CM codes

Insomnia is split between two chapters. G47.0- in the nervous system chapter holds G47.00 (insomnia, unspecified), G47.01 (insomnia due to medical condition), and G47.09 (other insomnia). F51.0- in the mental health chapter holds insomnia not due to a substance or known physiological condition: F51.01 primary insomnia, F51.02 adjustment insomnia, F51.03 paradoxical insomnia, F51.04 psychophysiologic insomnia, F51.05 insomnia due to other mental disorder, and F51.09 other.

G47.00 is the default when the provider documents only insomnia with no cause. G47.01 requires the underlying medical condition to be coded first. F51.05 requires the associated mental disorder (such as F41.1 or F33.9) to be coded as well. Chronic insomnia and conditioned insomnia index to F51.04 (psychophysiologic insomnia), not to G47.00, so a diagnosis of chronic insomnia lands in the mental health chapter unless the provider attributes it to a medical condition.

Insomnia caused by alcohol or drugs is coded to the substance category with the sleep disorder ending (for example F10.182 alcohol abuse with alcohol-induced sleep disorder), not to G47 or F51. Circadian rhythm disorders (G47.2-, including shift work type G47.26) and restless legs syndrome (G25.81) are distinct diagnoses and should be coded when documented rather than folded into insomnia.