Sleep disorders: comparison of ICD-11 and ICD-10.

The current article reviews adjustments that were made to the classification of sleep disorders in the 11th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-11) in comparison to the 10th revision of the coding system (ICD-10). A new chapter on sleep-wake disorders was introduced as chapter 7 in ICD-11, removing the distinction in nonorganic and organic sleep disorders that was used in ICD-10. The rationale for this was the commonsense notion that clinicians and researchers have difficulties to identify the etiology of insomnia and to establish causality between insomnia and coexisting conditions. With respect to sleep disorders that were previously included in chapter V "Mental and behavioural disorders" of the ICD-10, the following important changes were made: the diagnosis of insomnia disorder can now be made as comorbid with other mental disorders or physical illnesses if the insomnia symptoms are a focus of independent clinical attention, non-restorative sleep alone without difficulties initiating or maintaining sleep is not sufficient anymore to diagnose insomnia disorder and new diagnostic categories have been created, including insufficient sleep syndrome and sleep-related eating disorder. Future research will show whether the adjustments in ICD-11 will help clinicians to make reliable and clinically useful diagnoses and whether this improves routine clinical care for sleep disorders.