2006 ICD-9-CM Volume 1 Diagnosis Codes Home > Diseases Of The Nervous System And Sense Organs 320-389 > Inflammatory Diseases Of The Central Nervous System 320-327 > Sleep Disorders 327.* > 2006 ICD-9-CM Diagnosis 327.31 Circadian rhythm sleep disorder, delayed sleep phase type View the most recent version of ICD-9-CM 327.31 327.31 is a specific code that can be used to specify a diagnosis 327.31 contains 1 index entry View the ICD-9-CM Volume 1 327.* hierarchy  Index entries containing 327.31: Disorder - see also Disease sleep 780.50 circadian rhythm 327.30 delayed sleep phase type 327.31