# Clinical significance criteria in the ICSD and DSM sleep disorder classifications: a content overlap analysis using the Jaccard index

Christophe Gauld, Vincent P. Martin, Clélia Quilès, Pierre-Alexis Geoffroy, Julien Coelho, Pierre Philip, Régis Lopez, Jean-Arthur Micoulaud-Franchi

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Christophe Gauld, Vincent P. Martin, Clélia Quilès, Pierre-Alexis Geoffroy, Julien Coelho, et al. Clinical significance criteria in the ICSD and DSM sleep disorder classifications: a content overlap analysis using the Jaccard index. Journal of Clinical Sleep Medicine, 2025, 10.5664/jcsm.11570. hal-04919262

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Clinical significance criteria in the ICSD and DSM sleep disorder classifications: A content overlap analysis using the Jaccard index

This document is the author version of an article published in the *Journal of Clinical Sleep Medicine* in January 2025.

Doi: 10.5664/jcsm.11570

PMID: 39862150

**Running head:** Clinical significance criteria and sleep medicine

Christophe Gauld, MD, PhD ¹,²,³, Vincent P. Martin, PhD ⁴, Clélia Quilès, MD, PhD ⁵,⁶, Pierre-Alexis Geoffroy, MD, PhD ⁷,⁸,⁹, Julien Coelho, MD, PhD ³,⁵, Pierre Philip, MD, PhD ³,⁵, Régis Lopez, MD, PhD ¹⁰, Jean-Arthur Micoulaud-Franchi, MD, PhD ³,⁵,*

¹ Department of Child and Adolescent Psychopathology, CHU de Lyon, F-69000 Lyon, France

² Institut des Sciences Cognitives Marc Jeannerod, UMR 5229 CNRS & Université Claude Bernard Lyon 1, F-69000 Lyon, France

³ Univ. Bordeaux, CNRS, SANPSY, UMR 6033, F-33000 Bordeaux, France.

⁴ Deep Digital Phenotyping Unit, Department of Precision Health, Luxembourg Institute of Health, L-1445 Strassen, Luxembourg

⁵ Univ. Bordeaux, Inserm, Bordeaux Population Health Research Center, team pharmacoepidemiology, UMR 1219, F-33000 Bordeaux, France

⁶ Centre Hospitalier Charles Perrens, F-33000 Bordeaux, France

⁷ Département de psychiatrie et d'addictologie, AP-HP, GHU Paris Nord, DMU Neurosciences, Hopital Bichat - Claude Bernard, F-75018 Paris, France

⁸ Centre ChronoS, GHU Paris - Psychiatry & Neurosciences, 1 rue Cabanis, 75014 Paris, France

⁹ Université Paris Cité, Inserm, NeuroDiderot, F-75019 Paris, France

¹⁰ Institut des Neurosciences de Montpellier (INM), University Montpellier, 34000 Montpellier, France
* Corresponding author:

Jean-Arthur Micoulaud-Franchi, University Sleep Medicine Department, University Hospital
of Bordeaux, 33 076 Bordeaux, France, [jarthur.micoulaud@gmail.com](mailto:jarthur.micoulaud@gmail.com).
**Study Objectives.** Both the International Classification of Sleep Disorders (ICSD) and the Sleep-Wake disorders section of the Diagnostic and Statistical Manual (DSM) emphasize the importance of clinical judgment in distinguishing the normal from the pathological in sleep medicine. The DSM-IV (1994) introduced the Clinical Significance Criterion (CSC) to standardize this judgment and enhance diagnostic reliability.

**Methods.** This review conducts a theoretical and historical content analysis of CSC presence, frequency, and formulation in the diagnostic criteria of sleep disorders. Three steps were undertaken: i) selecting main sleep disorder classifications and main disorders within them, ii) systematically extracting CSC-related content, and iii) analyzing the evolution of CSC presence through quantification (Jaccard Index) and visualization (radar plots).

**Results.** The DSM-5-TR includes CSC in five of nine main sleep disorders, compared to two in the ICSD-3-TR (Circadian Rhythm Sleep-Wake Disorder and Nightmare Disorder). The overlap between DSM-5-TR and ICSD-3-TR is moderate (Jaccard Index = 0.40). The overlap between DSM versions is higher (0.53). Conversely, ICSD revisions exhibit minimal similarity (0.16). Radar plots reveal a gradual increase in CSC use within ICSD versions.

**Conclusions.** These results highlight the variable application of CSC in sleep disorder classifications. Universal CSC inclusion may not be essential, but systematic discussion of its potential use can help refine diagnostic criteria. This refinement is important for accurately diagnosing sleep disorders and better differentiating the normal from the pathological, a major challenge in sleep medicine.

**Keywords:** sleep disorders; distress; sleep health; sleep-wake classification; diagnosis; international classification of sleep disorders.
# Brief Summary

## Current Knowledge/Study Rationale:

* The clinical significance criterion (CSC) was introduced as a diagnosis criterion to standardize clinical judgment in distinguishing normal and pathological.

* A theoretical and historical analysis of CSC presence, frequency, and formulation within the diagnostic criteria of sleep disorders, remains lacking.

## Study Impact:

* This study provides a systematic extraction of CSC in ten sleep disorder classifications for nine sleep disorders; the use of CSC is not uniform across the International Classifications of Sleep Disorders (ICSDs) and the Sleep-Wake disorders section of the Diagnostic and Statistical Manuals (DSMs).

* Drawing the attention of the sleep community to the CSC in sleep disorder classification serves as a foundation to refine the diagnostic criteria of each sleep disorder, for more accurately establishing the diagnoses of it.
Introduction

Two cornerstone international classifications are primarily used by the sleep medicine community. The International Classification of Sleep Disorders (ICSD), established by the American Academy of Sleep Medicine (AASM) in 1990, is currently in its third revised version, updated in 2023.¹ In parallel, the Sleep-Wake Disorders section of the Diagnostic and Statistical Manual of Mental Disorders (DSM), overseen by the American Psychiatric Association (APA) since the DSM-III in 1980, is now in its fifth revised version, updated in 2022.²

Since the seminal work of the Diagnostic Classification of Sleep and Arousal Disorders (DCSAD) proposed in 1979 by the Association of Sleep Disorders Centers (ASDC) and the Association for the Psychophysiological Study of Sleep (APSS),³ various versions of these two classifications have shown a gradual historical progression in their general organization and in the list of diagnostic criteria for each sleep disorder.¹,²,⁴⁻⁹,⁹,¹⁰ The emergence of sleep disorder classifications since the seventies has enabled communication among clinicians and researchers, and has promoted the structuring and development of scientific knowledge and clinical practices concerning sleep disorders.¹¹ This widening of medical and scientific knowledge has in turn resulted in the evolution of the classification of sleep disorders.¹² Classifications are essential for positing that sleep medicine is a particular branch of medicine that concerns specific disorders, i.e. sleep disorders. Classifications are also essential for establishing codified diagnostic criteria that allow reliable diagnoses to be made by professionals on the basis of definitions of discrete sleep disorders that clearly differentiate the normal and the pathological for a given sleep condition.¹³ Indeed, diagnostic criteria avoid false positives (risk of “overmedicalization”, i.e. the unnecessary labeling of disorders) and false negatives (risk of “undermedicalization”, i.e. missing patients who require treatment).¹⁴,¹⁵ Furthermore, diagnostic criteria have to be validated by scientific research and can evolve over time.¹¹⁻¹³,¹⁶,¹⁷ The diagnostic criteria of sleep disorders included in the ICSDs and DSMs thus ensure that the procedure for diagnosing a sleep disorder is codified and shared. As such, diagnostic criteria participate in the operationalization of sleep disorder diagnoses, i.e. ensuring that a certain procedure may be undertaken or performed in a standardized way to make a diagnosis reliable in clinical practice and research.¹⁸⁻²⁰

Surprisingly, despite this operationalization of diagnoses, the introductions to almost all versions of the ICSD have underlined the role of “clinical judgment” (p.3 of the ICSD-1).⁴ As early as 1990, the first version of the ICSD attested that “the final assignment of a particular
diagnosis [and the] severity criteria usually depend upon clinical judgment" (p.8).⁴ The importance of clinical judgment is further emphasized in the ICSD-2, which states that "it is left to the clinical judgment of the individual clinician to determine what is clinically significant within the specific clinical context and what is not" (p.XVII)⁶ and in ICSD-3, where clinicians are told that "some degree of judgment is necessary in the application of these criteria" (p.14)⁷ – the same applying for objective measures which "must be used with appropriate clinical judgment" (p.144).⁷ Clinical judgment plays an essential role in the diagnostic process, not only in the identification, hierarchization and organization of the collection of symptoms, but also in distinguishing between the normal and the pathological.²¹⁻²³ However, clinical judgment is a complex process that is difficult to standardize and can depend heavily on the subjectivity of the clinician.²⁴,²⁵

Contrary to the ICSDs in which the notion of clinical judgment was introduced with very little thoughtful preliminary debate by the sleep community, the different versions of the DSM have benefited from numerous discussions in the field of psychiatry,²,⁸,⁹,⁹,¹⁰,²⁶,²⁷ with even a dedicated "Use of clinical judgment" section in the introduction of the DSM-IV (p.23)²⁸ and DSM-IV-TR (p.24).⁹ In the attempt to better standardize the role of clinical judgment, it was proposed that the criteria-qualifying (or "criteriological") approach could offer a more reliable way to define a condition as a disorder.²⁰,²⁹⁻³¹ A step forward in this sense was the proposal for a "Clinical Significance Criterion" (CSC) in the DSM-IV (1994).²⁸ Appearing in subsequent versions of the DSM, the CSC is considered as one of the diagnostic criteria, usually worded as follows: "the disturbance causes clinically significant distress or impairment in social, occupational, or other important areas of functioning" (p. 21).¹⁰ Thus, the CSC differs from the other diagnostic criteria (e.g., symptom criteria or polysomnographic criteria) by focusing on the harm (distress and/or impairment, reported by the patient or by others, such as the bed partner) caused by the disorder or the symptoms.³²⁻³⁷ An extensive literature has explicitly discussed and criticized the issues raised by such a criteria-qualifying approach to harm in psychiatry,³⁸⁻⁴² given that its aim is i) to harmonize the terminology used and operationalize the diagnostic process to delineate the normal and the pathological for a condition;³⁴ ii) to reduce the risk of false positives and false negatives, thereby helping to overt the risk of overmedicalization or undermedicalization.⁴³

In view of the importance and the controversies surrounding the CSC in psychiatry, several systematic extraction of CSC and comparisons and historical analyses of its use in the diagnostic criteria of various mental disorders have been conducted⁴⁴⁻⁴⁸ to pave the way for further validation and evolution of diagnostic criteria. However, a systematic extraction of
CSC, as well as a comparative analysis of its presence, frequency, and formulation within the diagnostic criteria of sleep disorders, remains lacking. This is despite a recent review highlighting the importance of “harm” in defining sleep disorders.⁴⁹ The present theoretical and historical review, which is based on a quantified (using the Jaccard index) and visualized (using dedicated radar plots) content analysis of the diagnostic criteria of the main sleep disorders, seeks to fill that gap by identifying, extracting and comparing the CSC in the successive versions and revisions of the main sleep disorder classifications. A focus will be placed on the use of the CSC within the latest updates ICSD-3-TR¹ and DSM-5-TR.²
## Material and Methods

To identify, extract and compare the CSC in the main sleep disorder classifications using our previous analysis of the diagnostic criteria of sleep disorders¹³ and symptom content overlap methodologies,⁵⁰⁻⁵³ a content analysis of the diagnostic criteria for the main sleep disorders in the main sleep disorder classifications was carried out. First, we selected the main sleep disorder classifications (defined as widely or currently used international sleep disorder classifications in clinical sleep medicine and by the sleep research communities, and employing a criteria-qualifying approach relying on a defined set of diagnostic criteria that must be fulfilled for a diagnosis to be established) and the main sleep disorders in them (defined as sleep disorders that have shaped the development of sleep medicine)¹¹,¹²,⁵⁴, then harmonized the labels for each main sleep disorder according to their wording in the ICSD-3-TR. Second, we systematically extracted the content of the CSC or its equivalent in the diagnostic criteria for each sleep disorder. Third, we conducted a quantified and visualized content overlap analysis to measure the similarity in the presence of the CSC or its equivalent in the diagnostic criteria of the sleep disorders in the ICSD-3-TR and the DSM-5-TR, but also in the subsequent versions of the ICSD and the DSM.

## Selection and labeling of main sleep disorders in main sleep disorder classifications

Ten main international sleep disorder classifications were selected: the DSM-III-R (1987),⁸ the ICSD (1990),⁴ the DSM-IV (1994),²⁸ the ICSD-R (1997),⁵ the DSM-IV-TR (2000),⁹ the ICSD-2 (2005),⁶ the DSM-5 (2013),¹⁰ the ICSD-3 (2014),⁷ the DSM-5-TR (2022)² and the ICSD-3-TR (2023).¹ The DCSAD (1979),³ the DSM-III (1980) (which incorporated the DCSAD as a sleep disorder section)⁸ and the International Classification of Diseases (ICD) of the World Health Organization (WHO)⁵⁵ were not included, despite being considered as an international sleep disorder classification, because they were not built on a criteria-qualifying approach, i.e., an explicit list of diagnostic criteria for sleep disorders.

Nine main sleep disorders were selected and the harmonized labels were the following: Chronic insomnia disorder, Narcolepsy (types 1 & 2), Idiopathic hypersomnia, Obstructive Sleep Apnea (OSA), Circadian rhythm sleep-wake disorder, Disorders of arousal, Rapid eye movement sleep Behavior Disorder (RBD), Nightmare disorder, Restless Leg Syndrome (RLS).¹ Since the terminology is not necessarily the same in the various versions of the selected main sleep disorder classifications, a transcoding matrix was created to harmonize the wording of the sleep disorders across the selected classifications. The names of sleep disorders for the various
classifications were all aligned with the most recent classification, i.e. the ICSD-3-TR.¹ For example, “Primary insomnia” in the DSM-IV-TR was labeled as “Chronic insomnia disorder”.⁵⁶,⁵⁷ This transcoding matrix was necessary to analyze the content overlap of diagnostic criteria across the different evolutions of the names of the sleep disorders (see **Supplementary Material 1**, “Harmonization of Disorder Labels”).

## CSC content extraction in diagnostic criteria of selected sleep disorders

Content extraction of CSC in the diagnostic criteria was conducted systematically for each selected main sleep disorder. To specifically extract the CSC content, all the diagnostic criteria were explored with a rigorous qualitative method by three independent authors, two sleep experts (JAM, CG) and one data processing expert (VM) with considerable experience of such analyses.¹³,⁵⁸⁻⁶¹ The extractions were adjusted until complete mutual approval. In the event of disagreement between the experts, consensus was sought by referring to another sleep expert and a psychiatrist expert (RL and CQ). CSC were identified in the diagnostic criteria of sleep disorders according to the definition found in the introduction of the DSM-5. The latter posits that “a generic diagnostic criterion [CSC] requiring distress or disability has been used to establish disorder thresholds, usually worded ‘the disturbance causes clinically significant distress or impairment in social, occupational, or other important areas of functioning”’ (p.21).¹⁰

Based on this definition, four characteristics of CSC were extracted from the diagnostic criteria: “clinically”, “significant” (referring to clinical judgment), “distress” (i.e., complaint, concern, suffering, discomfort or uneasiness related to sleep) and “disability” (i.e., impairment in one or more important areas of functioning).³² Diagnostic criteria of sleep disorders containing one to three of these four characteristics were termed “CSC-like”. When both CSC and CSC-like were found in the same sleep disorder, only the CSC was reported. **Supplementary Material 1** includes each selected sleep disorder within the different main classifications, the diagnostic criterion number containing the CSC or the CSC-like, the page within the classification manuals and the exact formulation of the diagnostic criterion containing the CSC or the CSC-like. **Supplementary Material 2** summarizes the presence or absence of CSC or CSC-like for each selected nine main sleep disorder in each selected ten main sleep disorder classification.

## Content overlap analysis of CSC and CSC-like between the ICSD-3-TR and the DSM-5-TR

A quantified content analysis using the Jaccard index was applied to the two most recent sleep disorder classifications: the ICSD-3-TR and the DSM-5-TR. The Jaccard index is a quantified
content overlap analysis considered as an established standard method.⁵⁰⁻⁵³ The values of this reference metric range from 0 to 1, where 0 indicates no similarity (no overlap) and 1 signifies complete similarity (full overlap) of the presence of CSC between the diagnostic criteria of the selected main sleep disorders. In line with previous studies, the Evans' Straightforward Statistics for the Behavioral Sciences rule of interpretation for the Jaccard index was used⁶²: very weak: (0.00-0.19), weak: (0.20-0.39), moderate: (0.40-0.59), strong: (0.60-0.79), and very strong: (0.80-1).

To focus the analysis on the use of the CSC or the CSC-like in the main sleep disorders outlined in the ICSD-3-TR and the DSM-5-TR, a table was developed. It summarizes, for each of the nine main sleep disorders, the presence or absence of CSC or CSC-like, the corresponding reference letter of the diagnostic criterion (e.g., “A.”) from which the CSC or the CSC-like was extracted, and the exact wording of the diagnostic criterion containing the CSC or the CSC-like. The presence or absence of an objective marker (i.e., a physiological marker related to a sleep disorder participating in the diagnosis)¹³ is noted for each of the nine main sleep disorder analyzed.

## Content overlap analysis of CSC and CSC-like between sleep disorder classifications

The overall number and percentage of identified CSC and CSC-like were computed for all the selected ten main sleep disorder classifications, based on **Supplementary Material 2**. The same metrics were computed for the DSMs and the ICSDs separately and compared using a Chi² test.

To quantify the overlap in the use of CSC across the different classifications, the Jaccard index was computed between all the classifications, the different versions of the ICSD and the different versions of the DSM.

The content overlap of CSC and CSC-like between the selected nine main sleep disorders was visualized using dedicated radar plots, where each concentric circle corresponds to a sleep disorder classification, and each radius corresponds to a sleep disorder. Such concentric visualizations illustrate the evolution of CSC use in the subsequent versions of the ICSDs and the DSMs classification, with older versions placed at the center and more recent version toward the periphery. The corresponding year of each classification was appropriately indicated within each circle. The presence of a CSC (full circle), the presence of a CSC-like (crossed circle), the absence of CSC or CSC-like (empty circle) and the absence of the sleep disorder in the classification (no circle) were differentiated. In this view, circles on the same radius refer to an overlap between classifications. The historical evolution of the four CSC and
CSC-like characteristics (“clinically”, “significant”, “distress”, “disability”) across time in the subsequent versions of the ICSDs and the DSMs was also visualized.
# Results

## Content overlap analysis of CSC and CSC-like between the ICSD-3-TR and the DSM-5-TR

In the latest updates ICSD and DSM sleep disorder classifications, the DSM-5-TR has more CSC (n=5 sleep disorders on 9) than the ICSD-3-TR (n=2, Circadian rhythm sleep-wake disorder and Nightmare disorder). The overlap between the ICSD-3-TR and the DSM-5-TR is thus moderate (Jaccard index=0.40), indicating some variation in the use of CSC between these two classifications.

Concerning the DSM-5-TR, only two sleep disorders did not have CSC or CSC-like: OSA and narcolepsy, which are the two sleep disorders containing objective biomarkers for the diagnosis. Despite having three CSC characteristics (out of four for a complete CSC), Idiopathic hypersomnia and RLS diagnostic criteria did not contain the term “clinically” (Table 1).

Concerning the ICSD-3-TR, no CSC or CSC-like was found for four sleep disorders (Narcolepsy, Idiopathic hypersomnia, Disorder of arousal, RBD). Except for Narcolepsy, CSC are present for these sleep disorders in the DSM-5-TR. A CSC-like appears for three sleep disorders (OSA, Insomnia disorder, RLS). Regarding OSA, while no CSC was found in the DSM-5-TR, an optional CSC-like was found in the ICSD-3-TR (this criterion is not necessary if the apnea hypopnea index is ≥ 15/h). For chronic insomnia disorder, a CSC-like was found in the ICSD-3-TR (with the use of the terms “dissatisfaction” suggesting distress, “impairments” suggesting disabilities), despite it being a complete CSC in the DSM-5-TR. For RLS, as in the DSM-5-TR, the CSC-like in the diagnostic criteria did not contain the CSC term “clinically”.

Regarding the exact wordings of the diagnostic criteria containing CSC and CSC-like in the DSM-5-TR, two variations were identified. The sleep manifestation associated with clinically significant distress or impairments can either involve the general notion of “sleep disturbance” (present in three sleep disorders) or specific terms related to a single sleep disorder, such as “hypersomnolence”, “episode”, “behavior”, “symptoms”, each of which appears only once. Moreover, the relationship between sleep manifestations and clinically significant distress or impairment is described using either the term “cause” in five sleep disorders or “accompanied” in two sleep disorders.

Regarding the exact wordings of the diagnostic criteria containing CSC and CSC-like in the ICSD-3-TR, the two CSC use the term “cause” to specify the relationship between sleep manifestations and clinically significant distress or impairments. However, the sleep
manifestations that cause clinically significant distress or impairment are various (sleep and wake disturbances for Circadian rhythm sleep-wake disorder and dream experiences for Nightmare disorder). Interestingly, for Nightmare disorder, a list of precise manifestations suggesting the distress, or the impairment is proposed. For RLS, “sleep disturbance” is an indicator of significant distress and not the cause of significant distress, as is usual in other CSC or CSC-like. The list of areas of functioning possibly impaired in the CSC of Nightmare disorder and CSC-like of RLS in the ICSD-3-TR add the mental and physical areas of functioning not explicitly found in the DSM-5-TR.

Lastly, concerning the general relations between CSCs and objective markers, **Table 1** shows that three sleep disorders present a CSC or a CSC-like, but no objective markers (chronic insomnia disorder, nightmare disorder, and RLS in the ICSD-3-TR and the DSM-5-TR), two sleep disorder has no CSC (nor CSC-like) but an objective marker (narcolepsy and hypersomnia idiopathic in the ICSD-3-TR), and one has both a CSC or a CSC-like and an objective marker (CRSWD and OSA in the ICSD-3-TR).
<table><caption>**Table 1.** Summarize of the use of the Clinical Significance Criteria (CSC) and CSC-like in the main sleep disorder retrieved in the International Classification of Sleep Disorders, third edition revised (ICSD-3-TR) and the Sleep disorders section of the Diagnostic and Statistical Manual of Mental Disorders, fifth edition revised (DSM-5-TR), with the indication of the presence or absence of an objective marker.</caption><thead><tr><th>Sleep disorders</th><th>DSM-5-TR criteria containing a CSC or a CSC-like</th><th>ICSD-3-TR criteria containing a CSC or a CSC-like</th><th>CSC or CSC-like in the DSM-5-TR</th><th>CSC or CSC-like in the ICSD-3-TR</th><th>DSM-5-TR formulation of the CSC or the CSC-like</th><th>ICSD-3-TR formulation of the CSC or the CSC-like</th><th>DSM-5-TR objective markers</th><th>ICSD-3-TR objective markers</th></tr></thead><tbody><tr><td>Chronic insomnia disorder</td><td>B.</td><td>B.2, B.3, B.9</td><td>✓</td><td>CSC-like</td><td>The sleep disturbance causes <u>clinically significant distress or impairment</u> in social, occupational, educational, academic, behavioral, or other important areas of <u>functioning</u>.</td><td>B2. Attention, concentration, or memory <u>impairment</u>.<br>B3. Impaired social, family, occupational, or academic performance.<br>B9. Concerns about or <u>dissatisfaction</u> with sleep.</td><td>—</td><td>—</td></tr><tr><td>Narcolepsy (types 1 & 2)</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td><td>CSF hypocretin-1 / MSLT</td><td>CSF hypocretin-1 / MSLT</td></tr><tr><td>Idiopathic hypersomnia*</td><td>C.</td><td>—</td><td>CSC-like</td><td>—</td><td>The hypersomnolence is <u>accompanied by significant distress or impairment</u> in <u>cognitive, social, occupational, or other important areas of functioning</u>.</td><td>—</td><td>—</td><td>MSLT/ 24-hour polysomnography or actigraphy</td></tr><tr><td>Obstructive sleep apnea (OSA)</td><td>—</td><td>A.1</td><td>—</td><td>CSC-like</td><td>—</td><td>The patient <u>complains of</u> sleepiness or insomnia, or other symptoms leading to <u>impaired</u> sleep-related quality of life.</td><td>AHI</td><td>AHI</td></tr><tr><td>Circadian rhythm sleep-wake disorder – General criteria</td><td>C.</td><td>C.</td><td>✓</td><td>✓</td><td>The sleep disturbance causes <u>clinically significant distress or impairment</u> in social, occupational, and other important areas of <u>functioning</u>.</td><td>The sleep and wake disturbances <u>cause clinically significant distress or impairment</u> in <u>mental, physical, social, occupational, educational, or other important</u></td><td>—</td><td>Actigraphy</td></tr></tbody></table>
<table><tr><td>Disorder of arousal – General criteria</td><td>D.</td><td>—</td><td>✓</td><td>—</td><td>The episodes cause <u>clinically significant distress or impairment</u> in social, occupational, or other important areas of <u>functioning</u>.</td><td>—</td><td>—</td><td>—</td></tr><tr><td>Rapid eye movement sleep behavior disorder (RBD)</td><td>E.</td><td>—</td><td>✓</td><td>—</td><td>The behaviors cause <u>clinically significant distress or impairment</u> in social, occupational, or other important areas of <u>functioning</u> (which may include injury to self or the bed partner).</td><td>—</td><td>Polysomnography</td><td>Polysomnography</td></tr><tr><td>Nightmare disorder</td><td>C.</td><td>C.</td><td>✓</td><td>✓</td><td>The sleep disturbance causes <u>clinically significant distress or impairment</u> in social, occupational, or other important areas of <u>functioning</u>.</td><td>The dream experience, or the sleep disturbance produced by awakening from it, causes <u>clinically significant distress or impairment</u> in social, occupational, or other important areas of <u>functioning</u> as indicated by the report of at least one of the following: [...]</td><td>—</td><td>—</td></tr><tr><td>Restless leg syndrome (RLS)</td><td>C.</td><td>C.</td><td>CSC-like</td><td>CSC-like</td><td>The symptoms in <u>Criterion A</u> are accompanied by <u>significant distress or impairment</u> in social, occupational, educational, academic, behavioral, or other important areas of <u>functioning</u>.</td><td>The symptoms of RLS cause <u>concern, distress, sleep disturbance, or impairment</u> in social, occupational, educational, behavioral, or other important areas of <u>functioning</u>.</td><td>—</td><td>—</td></tr></table>

<footnote>* Hypersomnolence disorder for the DSM-5-TR. Sleep disorder labels are those of the ICSD-3-TR, as presented in the transcoding matrix, which harmonizes the wording of sleep disorders across the selected classifications (Supplementary Material 1). Green: CSC; Orange: CSC-like; Red: absence of CSC. A similar wording analysis of all the selected main classifications for four sleep disorders (Chronic insomnia disorder, OSA, Idiopathic hypersomnia and Circadian rhythm sleep disorders-wake disorder) is presented in Supplementary material 3. CSC formulations are in bold; notable wordings presented in the results related section are underlined. AHI: Apnea-Hypopnea Index; CSF: CerebroSpinal Fluid; MSLT: Multiple Sleep Latency Test.</footnote>
## Content overlap analysis of CSC and CSC-like between sleep disorder classifications

The diagnostic criteria of 82 sleep disorders were also analyzed from all the selected classifications in which 24 CSC (29.3%), 33 CSC-like (40.2%) and 25 disorders without CSC or CSC-like (30.5%) were identified.¹,²,⁴⁻⁹,⁹,¹⁰ A similar number of diagnostic criteria from the DSMs (45.1% from the 82 sleep disorders analyzed) and the ICSDs (54.9%) were analyzed for the presence of CSC or CSC-like. Significantly more CSC were extracted from the DSMs (83.3% of the 24 total CSC) than from the ICSDs (16.7%). Conversely, significantly fewer CSC-like were extracted from the DSMs (24.2% of the 33 total CSC-like) than from the ICSDs (75.8%). Lastly, significantly fewer DSM sleep disorders (36% of the 25 total disorders without CSC or CSC-like) did not have either a CSC or a CSC-like than in the ICSD (64%). **Table 2.**

**Table 2.** Number of sleep disorder having a Clinical Significance Criteria (CSC), a CSC-like or neither one or the other in the five selected versions of the International Classifications of Sleep Disorders (ICSDs) and the five selected versions of the Sleep disorders section of the Diagnostic and Statistical Manual of Mental Disorders (DSMs).

<table><thead><tr><th></th><th>CSC</th><th>CSC-like</th><th>No CSC & nor CSC-like</th><th>Total number of sleep-wake disorders</th></tr></thead><tbody><tr><td>DSMs <sup>2,8,9,9,10</sup></td><td>20</td><td>8</td><td>9</td><td>37</td></tr><tr><td>ICSDs <sup>1,4-7</sup></td><td>4</td><td>25</td><td>16</td><td>45</td></tr><tr><td>Total number of sleep-wake disorders</td><td>24</td><td>33</td><td>25</td><td>82</td></tr></tbody></table>

The distribution difference between the DSM and the ICSD is significant: X2 (5, N = 82) = 20.8, p = 3e-5. CSC: Clinical Significance Criteria; DSM: Sleep disorders section of the Diagnostic and Statistical Manual of Mental Disorders; ICSD: International Classification of Sleep Disorders.

The quantified Jaccard index between the different versions of the DSMs and the ICSDs is shown in **Table 3**. Although in the moderate range (0.53), the average overlap between the five selected versions of the DSM reflected an attempt at standardization in the use of the CSC across the diagnostic criteria. Conversely, the Jaccard index for the different versions of the ICSD was only 0.16, indicating a very weak similarity and a wide variation in the use of CSC across the diagnostic criteria. In line with these results, the overall overlap across all the selected classifications and diagnostic criteria was weak (0.24).
<table><caption>**Table 3.** Jaccard index of the Clinical Significance Criteria (CSC) between sleep disorder classifications. The detailed information from this Table is graphically presented in **Figure 1-A** and **Figure 1-B**.</caption><thead><tr><th>Overlap between sleep disorder classifications</th><th>Between all selected sleep disorder classifications</th><th>Between the five versions of the DSM 2.8,9,9,10</th><th>Between the five versions of the ICSD 1.4-7</th><th>Between DSM-5-TR and ICSD-3-TR</th></tr></thead><tbody><tr><th>Jaccard Index</th><td>0.24</td><td>0.53</td><td>0.16</td><td>0.40</td></tr></tbody></table>

DSM: Sleep disorders section of the Diagnostic and Statistical Manual of Mental Disorders; ICSD: International Classification of Sleep Disorders.

The content overlap of CSC and CSC-like between the selected sleep disorders is shown in **Figure 1a** for the different versions of the DSMs and **Figure 1b** for the different versions of the ICSDs.<sup>1,2,4-9,9,10</sup> A global figure combining the two is available in **Supplementary Figure 1**.

<figure><img src="image_2.png" /><figcaption>**Figure 1.** Overlap of the Clinical Significance Criterion (CSC) and CSC-like in the five selected versions of the ICSD (left) and the five selected versions of the DSM (right). Each concentric circle represents a classification (the older version is in the center, the more recent version at the periphery, and the year of each classification is indicated on the circle appropriately), each represents a CSC (filled circle), a CSC-like (crossed circle) or the absence of a CSC in a disorder (empty circle). Each radius is associated with a sleep disorder labeled according to the harmonization based on the ICSD-3-TR formulations. Two or more circles on the same radius refer to an overlap between classifications. DSM: Sleep disorders section of the Diagnostic and Statistical Manual of Mental Disorders; ICSD: International Classification of Sleep Disorders; IH: Idiopathic hypersomnia; OSA: Obstructive sleep apnea; CRSWD:</figcaption></figure>
Circadian rhythm sleep-wake disorder; DA: Disorders of arousal; RBD: Rapid eye movement sleep Behavior Disorder; Restless Leg Syndrome (RLS). The summarized information in terms of Jaccard index, from this figure, is presented in **Table 3**.

The historical evolution of the CSC and CSC-like and their four characteristics (“clinically”, “significant”, “distress”, “impairment”) in the different sleep disorders of the different classifications is shown in **Figure 2**. While terms related to distress and disability are identified as early in the first selected versions of the DSM 8 and the ICSD 4, the notion of “clinically” appears later in the DSM-IV 28 and in the ICSD-3 7 respectively. “Significance” appears very early in the DSM 8 (at the same time as “disability” and “distress”), but only with the ICSD-3 7 (at the same time as “clinically”). A complete CSC appears for the first time in the DSM-IV,28 but only in the ICSD-3.7 The notion of CSC (CSC-like) appears first in the DSM-III-TR 8 (using the terms “complaint of” and “impaired daytime functioning”), formulated as a complete CSC in the majority of sleep disorders in the DSM-IV,28 and persists in its subsequent text revision and versions.2,9,10 The notion of CSC appears in the first version of the ICSD (by the term “complaint of”) as a CSC-like,4 and was formulated as a complete CSC only in two sleep disorders in the ICSD-3.7 Lastly, except for the disappearance of the “clinically” CSC characteristic for idiopathic hypersomnia, the acquisition of a full CSC in one classification always spreads to subsequent classifications.

<figure><img src="image_3.png" /><figcaption>**Figure 2.** Characteristics of the Clinical Significance Criterion (CSC) and CSC-like across the selected sleep disorders-wake classifications. Each disorder is assigned to a specific color. The presence of each characteristic is represented by a colored circle under its column. The semi-circles correspond to the presence of terms that are sufficiently close to the CSC characteristics:</figcaption></figure>
"complaint" or "dissatisfaction" instead of distress, "sufficiently severe" instead of significant, "impaired sleep-related quality of life" instead of disability. DSM: Sleep disorders-Wake section of the Diagnostic and Statistical Manual of Mental Disorders; ICSD: International Classification of Sleep Disorders. C: "Clinically"; S: "Significant"; Ds: "Distress"; Db: "Disability". IH: Idiopathic hypersomnia; OSA: Obstructive sleep apnea; CRSWD: Circadian rhythm sleep-wake disorder; DA: Disorders of arousal; RBD: Rapid eye movement sleep Behavior Disorder; Restless Leg Syndrome (RLS).
Discussion

The role of CSC is to allow clinicians to differentiate the normal from the pathological in the
diagnostic process and to reduce the risk of overmedicalization or undermedicalization for
mental and sleep disorders.¹³,³⁴,⁴³ Using a quantified and visualized content analysis, we present
a theoretical and historical review that explores the presence, frequency and formulation of the
CSC within the main sleep disorders. First, we examine the variations in how the CSC is
incorporated across the main sleep disorder classifications, with a specific focus on the
differences between the ICSD-3-TR and the DSM-5-TR. We then discuss the implications of
incorporating the CSC into each main sleep disorder, addressing the challenges related to its
application in sleep medicine.

Place of CSC in the various main sleep disorder classifications

Concerning the variations in how the CSC is incorporated into the main sleep disorder
classifications, the present study found that a large number of sleep disorder criteria do not
contain a CSC: 17 out of 37 in the different versions of the DSM and 41 out of 45 in the
different versions of the ICSD, with a significant frequency difference between the DSMs and
the ICSDs. The ICSDs use CSC less frequently than the DSMs, a difference that remains
between the ICSD-3-TR and in the DSM-5-TR (Table 2). Our content analysis is original in
that it evaluated the degree of similarity (and thus heterogeneity) of presence of CSC between
classifications across nine main sleep disorders in ten versions of the ICSDs and DSMs.
Notably, the presence of the CSC over time was more heterogeneous in the ICSDs than in the
DSMs (Table 3; Figure 1).

The results show that the CSC appeared earlier and was used more systematically in the DSM
sleep-wake disorders sections than in the ICSDs (Figure 2). For example, the CSC first
appeared in the DSM-IV (1994),²⁸ i.e. twenty years before figuring in the ICSD-3 (2014).⁷ This
anteriority of the DSM regarding the CSC – as well as its wide subsequent use – has been
underpinned by the fruitful discussions that have taken place in the psychiatric community
regarding its application in the operationalization of the normal and the pathological since the
70s,¹⁹,²⁹,³¹,⁶³ debate that persists to this day.⁶⁴ For instance, in the DSM-IV almost half of the
entries for mental disorders incorporate the CSC.⁴³ In the sleep-wake disorders section of the
DSM-5-TR, 5/9 (55.5%) main sleep disorders contain a CSC. In contrast, in the ICSD-3-TR,
only two main sleep disorders (circadian sleep-wake disorder and nightmare disorder) specify
a CSC (22.2 %). Despite its underrepresentation, however, the CSC has become more prevalent
in the ICSD, albeit with a few years delay.

The appearance of the CSC in the various classifications may be driven by the permanent quest
for innovation that guides the revisions of diagnostic criteria, a principle of continuous
innovation.⁶⁵⁻⁶⁷ However, once a CSC appears for a sleep disorder in the ICSD, it stays there
and tends no longer to evolve. This means that the conservation of the CSC in a sleep disorder
may be underpinned by principle of prudential conservatism that also guides the revision of the
diagnostic criteria so that they remain stable.⁶⁵⁻⁶⁷ By striking a balance between these two
principles, it is possible to stabilize the diagnostic criteria over time and to harmonize the ICSD
and the DSM, while leaving room for discussion during each revision. Unfortunately, the
underlying processes guiding the use of the CSC during the revision of sleep disorder
classifications has received very little attention until now.¹¹⁻¹³ This absence of direction has led
to high heterogeneity in the wording of the CSC-like.

Further studies should address the historical and sociopolitical context surrounding the
development of the DSMs and ICSDs to better understand the different emergence of CSCs in
the diagnostic criteria of these sleep disorder classifications.⁶⁸ Such studies could benefit from
interdisciplinary approaches, including sociological or anthropological frameworks.²²,⁶⁹,⁷⁰
Nevertheless, the less frequent, more heterogeneous, and less systematic use of CSC, as well
as its later adoption in the diagnostic criteria of various ICSD versions compared to the DSM,
did not compromise the quality of ICSD diagnostic criteria development. The ICSD criteria
were specifically developed within the field of sleep medicine, guided by a thoughtful and
sophisticated nosological framework. This approach aimed to address challenges related to
sleep manifestations, particularly insomnia and sleepiness symptoms,¹³ and polysomnographic
markers.⁷¹ However, as the ICSD begins incorporating the CSC into the diagnostic criteria of
some sleep disorders, it is important for the sleep medicine community to explicitly discuss
this integration. Insights from psychiatric literature may help refine diagnostic criteria,
provided they are tailored to the unique characteristics of each sleep disorder. This
consideration is particularly relevant because sleep disorders appear more heterogeneous
compared to mental disorders, which have adhered to a general and unified definition of what
a mental disorder is since the DSM-3. This unified approach remains a topic of ongoing debate
for sleep disorders.⁴⁹ To specifically address the relevance of CSC, the following discussion
examines the challenges associated with its use in relation to the specificities of sleep disorders.

*CSC challenge in various specific main sleep disorders*
### CSC challenge of causality: the case of Circadian rhythm sleep-wake disorder (CRSWD)

CRSWD is one of the sleep disorders where the CSC appeared comparatively early in the diagnostic criteria. CRSWD is characterized by an impairment of the internal circadian rhythm or a misalignment between the internal circadian rhythm and the required external timing of social activities.⁷ However, regarding the latter subtype, the severity of the misalignment in itself is not sufficient to assess its pathological nature ⁷²,⁷³: its consequences in terms of distress or impairment in social, occupational, or other important areas of functioning is necessary to establish the diagnosis. A major challenge of using the CSC in sleep disorder classifications is raised by the specific case of CRSWD: establishing causality between the sleep and wake disturbances (in terms of dysfunction) and the harm (i.e., a distress or impairment / disability).⁷² Such causality is in line with the hybrid framework of harmful dysfunction analysis (HDA), which has been used for more than thirty years⁷⁴ HDA considers that (sleep) disorders comprise a physiological dysfunction that directly causes harm to an individual.⁷⁴,⁷⁵ However, in the present content analysis, some CSC-like in the DSM-5-TR mean that the notion of causality is replaced by the vague and rather imprecise notion of “association”. The specific case of the CSC in the CRSWD underlines the need for complementary research to unravel the underlying mechanisms between the sleep dysfunction and the harm in sleep disorder.

### CSC challenge of harmful symptoms: the cases of insomnia and nightmare disorders

Insomnia disorder have included a CSC in their diagnostic criteria since the DSM-IV, unlike the ICSDs. That absence seems to have been offset by the presence of diurnal symptoms associated with the nocturnal symptoms of insomnia disorder.⁵⁶,⁷⁶,⁷⁷ This issue in this particular case is that some symptoms of insomnia disorder can themselves be considered as harmful.³⁸,⁷⁵ Indeed, debate persists whether the harm is carried by the symptom or contained within the symptom, or if the harm is a causal consequence of the symptom.⁴¹,⁴¹,⁴³,⁷⁴,⁷⁸

In the ICSD-3 and 3-TR, the CSC of nightmare disorder has a broad range of sub-criteria, including diurnal symptoms (daytime sleepiness, fatigue or low energy mood disturbance, behavioral problems), distress (bedtime anxiety, fear of subsequent nightmares) and impairments (in occupational or interpersonal/social function). Such a mixture is not found in the DSM-IV, IV-TR, 5 and 5-TR. This set of mixed symptoms and harms highlights the ICSD's conceptors' concern for completeness in the diagnostic criteria of this sleep disorder. It is the
only main sleep disorder in the ICSD where we identified an attempt to specify sleep harm in
a CSC was.

In his work on patient-reported outcomes (PRO) for sleep harm, Buysse distinguished sleep
disturbance (i.e., sleep-related distress or sleep complaints referring to the quality and/or
satisfaction of sleep) from sleep-related impairment (i.e., sleepiness and awakening-related
distress or disability related to sleep impairment).<sup>79</sup> However, no explicit or consensual
terminology are used in the sleep medicine literature, so the terms are employed with diverse
meanings, despite the consensus that harmonization is needed to guarantee better reliability.<sup>80,81</sup>
In particular, the term *sleep disturbance* can refer either to *sleep dysfunction* (in physiological
terms)<sup>79</sup> or to *sleep harm* (in terms of values, and more precisely in terms of night-related sleep
distress),<sup>49,82</sup> The specific case of the CSC in insomnia and nightmare disorders highlights the
need for complementary studies on establishing a consensual terminology, a reliable measure
and a valid threshold of the clinical manifestations associated with harm in sleep medicine and
on the added value of the CSC when a sleep symptom is considered as explicitly harmful.

CSC challenge regarding objective markers: the cases of central hypersomnolence disorders
and OSA

Regarding narcolepsy, neither the ICSDs nor the DSMs include a CSC in their diagnostic
criteria. However, a biomarker is used to delineate the normal and the pathological (i.e., mean
sleep latency test (MSLT) of ≤ 8 minutes and two or more sleep-onset REM periods for
Narcolepsy Type (NT)-1 and NT-2; CSF hypocretin-1 concentration measured by
radioimmunoassay, ≤ 110 pg/mL for NT-1).¹ One hypothesis explaining the absence of CSC
as proposed by Spitzer, the architect of the DSM-III and reflected in its versions, is that the
addition of objective biomarkers would circumvent the very need for a CSC. As Spitzer and
Wakefield stated in 1999, the inclusion of a CSC is useful only as a “temporary measure” until
“better methods are developed to delineate the boundary between normal and pathological”.⁴³
In the case of narcolepsy, it is implicitly posited that the established fixed thresholds for the
objective criterion are strongly related both to dysfunction and to harm.⁸³ Interestingly, similar
objective criteria (MSLT of ≤ 8 minutes and/or total 24-hour sleep time ≥ 660 minutes) have
been proposed for hypersomnia disorder in the ICSD-3-TR, but not for hypersomnolence
disorder in the DSM-5-TR, hence proposing a CSC-like (and even a CSC in the DSM-IV).⁸⁴,⁸⁵
More generally, our results show a lack of a clear relationship between the inclusion of a CSC
and an objective marker across sleep disorders, and across ICSD-3-TR and DSM-5-TR. The
specific case of the CSC in central hypersomnolence disorders highlights the need for a more
thorough discussion regarding the role of CSC in relation to objective sleep markers.⁴⁹

Beyond a single objective marker, the possibility of a multicomponent bio-clinical marker
should also be considered. For OSA, neither the ICSDs nor the DSMs include diagnostic
criteria that involve a CSC. The biomarker that could offer a possible diagnostic criterion
distinguishing the normal from the pathological is the apnea hypopnea index (AHI). However,
unlike narcolepsy and idiopathic hypersomnia, the AHI is currently the subject of heated debate
in the sleep community.⁸⁶ More informative metrics of harm related to breathing obstruction
during sleep are clearly required.⁸⁶⁻⁸⁸ Among the possible candidates, the ICSD-3-TR has
included new clinical metrics related to patient-reported outcome measures (PROMs)
evaluating sleep harm,⁸⁹,⁹⁰ but has omitted to include biological ones such as hypoxic burden
and heart rate variability. Recent propositions include multicomponent grading systems like
the Baveno classification⁸⁶⁻⁸⁸ and the Swedish Sleep Apnea Registry (SSAR).⁹¹ A development
would be to design a bio-clinical “nomogram” integrating multiple parameters.⁹²⁻⁹⁴ The
specific case of the CSC in OSA highlights the need for research on how a multicomponent
bio-clinical marker could be included in the diagnostic criteria of sleep disorder.

*CSC challenge of harmonizing the main current sleep disorder classifications: the case of
parasomnia disorders*

A CSC for parasomnia disorders has been present since the DSM-IV for arousal disorders (NREM parasomnia disorder) and since the DSM-5 for RBD (REM parasomnia disorder) but has never appeared in any version of the ICSD. The use of CSC in the DSM seems to “help establish the threshold for the diagnosis of a disorder in those situations in which the symptomatic presentation by itself (particularly in its milder forms) is not inherently pathological”.¹⁰ A recent literature review suggested adding a CSC for the diagnostic criteria of NREM parasomnias in the ICSD.⁹⁵ The authors proposed adding a CSC to “individualize patients with an NREM parasomnia disorder from those having rare, mild and non-bothersome episodes of NREM parasomnia, as already proposed for the diagnosis of sleep-related rhythmic movement disorder in the ICSD-3-TR”.⁵⁸,⁹⁶,⁹⁷ The specific case of the CSC in arousal disorders highlights the need to better identify sleep disorders for which a CSC is mandatory and to harmonize this use between sleep disorder classification in order to enhance the inter-classification reliability of the diagnosis.
## Conclusion

Several fundamental challenges raised by this theoretical and historical review could help in elucidating the processes guiding the revision of sleep disorder classifications, particularly in the context of whether or not to implement the CSC. First, is there a causal relationship between the mechanism of the disorder and the harm? Second, do some sleep symptoms by themselves cause harm? And how will sleep clinicians understand the criteria related to harm for a specific sleep condition? Third, under what circumstances can a biomarker criterion replace the evaluation of harm so that clinicians can distinguish the normal and the pathological in a specific sleep condition? Finally, how can the use of CSC be harmonized across the main current sleep disorder classifications? The sleep research community has discussed these challenges and controversies and has proposed responses for each main sleep disorders. While encouraging evidence-based data obtained by rigorous research to develop more reliable and valid classifications, no overarching framework has been proposed to better structure the development of diagnostic criteria across sleep disorders and classification systems. Such a framework has been notably discussed in regard to the use of the CSC in psychiatry that could be inspiring and structuring for sleep medicine.43,44,46,48 However, it does not involve the universal inclusion of a CSC for all sleep disorder diagnostic criteria in the future versions of the ICSD. Sleep disorder classification requires indeed some nosological flexibility98,99 and conceptual humility100 for research and clinical practice. Nevertheless, discussing the potential use of CSC can help to refine diagnostic criteria of each main sleep disorder for more accurately establishing the diagnoses of sleep disorders and differentiating the normal from the pathological, a major challenge in sleep medicine.
Abbreviations

AASM: American Academy of Sleep Medicine

AHI: Apnea Hypopnea Index

APSS: Association for the Psychophysiological Study of Sleep

ASDC: Association of Sleep Disorders Centers

CRSWD: Circadian rhythm sleep-wake disorder

CSC: Clinical Significance Criterion

DCSAD: Diagnostic Classification of Sleep and Arousal Disorders

DIMS: Disorders of initiating and maintaining wakefulness

DOES: Disorders of excessive somnolence

DSM: Diagnostic and Statistical Manual of Mental Disorders

HDA: Harmful Dysfunction Analysis

ICD: International Classification of Diseases

ICSD: International Classification of Sleep Disorders

MSLT: Mean Sleep Latency Test

NREM: Non-Rapid Eye-Movement

OSA: Obstructive Sleep Apnea

PRO: Patient-Reported Outcome

PROMs: Patient-Reported Outcome Measures

PSG: Polysomnography

RBD: Rapid eye movement sleep Behavior Disorder

RLS: Restless Leg Syndrome

SSAR: Swedish Sleep Apnea Registry

SRBD: Sleep-Related Bruxism Disorder
# Acknowledgments

None.

# Declaration of competing interest

All the authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers' bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this review.

# Declaration of generative AI and AI-assisted technologies in the writing process

Not used for this research.

# Authors contributions:

**Gauld Christophe**: Writing – original draft preparation, Conceptualization; **Vincent P. Martin**: Writing – review and editing, Methodology, Visualization, Data curation (extraction), Resources; **Clélia Quilès**: Supervision, Reviewing, Validation; **Geoffroy Pierre-Alexis**: Supervision, Reviewing, Validation; **Julien Coelho**: Writing – review and editing; **Pierre Philip**: Supervision, Reviewing, Validation; **Lopez Regis**: Formal analysis, Reviewing, Editing, Validation; **Micoulaud-Franchi Jean-Arthur**: Writing – review and editing, Editing, Formal analysis, Supervision, Methodology, Validation.

# Data availability statement

The analysis notebook and the data used to generate the results of this article are available online: https://github.com/vincentpmartin/csc/content-analysis.

# Funding sources

No funding was received for this work.

# Ethical approval

Not required for this review.
## Supplementary Materials

<figure><img src="image_4.png" /><figcaption>Supplementary Figure 1</figcaption></figure>

### Supplementary Material 1

### Supplementary Material 2

### Supplementary Material 3

All the analysis notebook and the data used to generate the results of this article are available online: https://github.com/vincentpmartin/csc/content-analysis.
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**Figure Titles and Captions**

**Figure 1.** Overlap of the Clinical Significance Criterion (CSC) and CSC-like in the five selected versions of the ICSD (left) and the five selected versions of the DSM (right). Each concentric circle represents a classification (the older version is in the center, the more recent version at the periphery, and the year of each classification is indicated on the circle appropriately), each represents a CSC (filled circle), a CSC-like (crossed circle) or the absence of a CSC in a disorder (empty circle). Each radius is associated with a sleep disorder labeled according to the harmonization based on the ICSD-3-TR formulations. Two or more circles on the same radius refer to an overlap between classifications. DSM: Sleep disorders section of the Diagnostic and Statistical Manual of Mental Disorders; ICSD: International Classification of Sleep Disorders; IH: Idiopathic hypersomnia; OSA: Obstructive sleep apnea; CRSWD: Circadian rhythm sleep-wake disorder; DA: Disorders of arousal; RBD: Rapid eye movement sleep Behavior Disorder; Restless Leg Syndrome (RLS). The summarized information in terms of Jaccard index, from this figure, is presented in **Table 3**.

**Figure 2.** Characteristics of the Clinical Significance Criterion (CSC) and CSC-like across the selected sleep disorders-wake classifications. Each disorder is assigned to a specific color. The presence of each characteristic is represented by a colored circle under its column. The semi-circles correspond to the presence of terms that are sufficiently close to the CSC characteristics: “complaint” or “dissatisfaction” instead of distress, “sufficiently severe” instead of significant, “impaired sleep-related quality of life” instead of disability. DSM: Sleep disorders-Wake section of the Diagnostic and Statistical Manual of Mental Disorders; ICSD: International Classification of Sleep Disorders. C: “Clinically”; S: “Significant”; Ds: “Distress”; Db: “Disability”. IH: Idiopathic hypersomnia; OSA: Obstructive sleep apnea; CRSWD: Circadian rhythm sleep-wake disorder; DA: Disorders of arousal; RBD: Rapid eye movement sleep Behavior Disorder; Restless Leg Syndrome (RLS).
<table><caption>**Table 1.** Summarize of the use of the Clinical Significance Criteria (CSC) and CSC-like in the main sleep disorder retrieved in the International Classification of Sleep Disorders, third edition revised (ICSD-3-TR) and the Sleep disorders section of the Diagnostic and Statistical Manual of Mental Disorders, fifth edition revised (DSM-5-TR), with the indication of the presence or absence of an objective marker.</caption><thead><tr><th>Sleep disorders</th><th>DSM-5-TR criteria containing a CSC or a CSC-like</th><th>ICSD-3-TR criteria containing a CSC or a CSC-like</th><th>CSC or CSC-like in the DSM-5-TR</th><th>CSC or CSC-like in the ICSD-3-TR</th><th>DSM-5-TR formulation of the CSC or the CSC-like</th><th>ICSD-3-TR formulation of the CSC or the CSC-like</th><th>DSM-5-TR objective markers</th><th>ICSD-3-TR objective markers</th></tr></thead><tbody><tr><td>Chronic insomnia disorder</td><td>B.</td><td>B.2, B.3, B.9</td><td>✓</td><td>CSC-like</td><td>The sleep disturbance causes <u>clinically significant distress or impairment</u> in social, occupational, educational, academic, behavioral, or other important areas of <u>functioning</u>.</td><td>B2. Attention, concentration, or memory <u>impairment</u>.<br>B3. <u>Impaired</u> social, family, occupational, or academic performance.<br>B9. Concerns about or <u>dissatisfaction</u> with sleep.</td><td>—</td><td>—</td></tr><tr><td>Narcolepsy (types 1 & 2)</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td><td>—</td><td>CSF hypocretin-1 / MSLT</td><td>CSF hypocretin-1 / MSLT</td></tr><tr><td>Idiopathic hypersomnia*</td><td>C.</td><td>—</td><td>CSC-like</td><td>—</td><td>The hypersomnolence is <u>accompanied by significant distress or impairment</u> in <u>cognitive, social, occupational, or other important areas of functioning</u>.</td><td>—</td><td>—</td><td>MSLT/ 24-hour polysomnography or actigraphy</td></tr><tr><td>Obstructive sleep apnea (OSA)</td><td>—</td><td>A.1</td><td>—</td><td>CSC-like</td><td>—</td><td>The patient <u>complains of</u> sleepiness or insomnia, or other symptoms leading to <u>impaired</u> sleep-related quality of life.</td><td>AHI</td><td>AHI</td></tr><tr><td>Circadian rhythm sleep-wake disorder – General criteria</td><td>C.</td><td>C.</td><td>✓</td><td>✓</td><td>The sleep disturbance causes <u>clinically significant distress or impairment</u> in social, occupational, and other important areas of <u>functioning</u>.</td><td>The sleep and wake disturbances <u>cause clinically significant distress or impairment</u> in <u>mental, physical, social, occupational, educational, or other important</u></td><td>—</td><td>Actigraphy</td></tr></tbody></table>
<table><tr><td>Disorder of arousal – General criteria</td><td>D.</td><td>—</td><td>✓</td><td>—</td><td>The episodes cause <strong>clinically significant distress</strong> or <strong>impairment</strong> in social, occupational, or other important areas of <strong>functioning</strong>.</td><td>—</td><td>—</td><td>—</td></tr><tr><td>Rapid eye movement sleep behavior disorder (RBD)</td><td>E.</td><td>—</td><td>✓</td><td>—</td><td>The behaviors cause <strong>clinically significant distress</strong> or <strong>impairment</strong> in social, occupational, or other important areas of <strong>functioning</strong> (which may include injury to self or the bed partner).</td><td>—</td><td>Polysomnography</td><td>Polysomnography</td></tr><tr><td>Nightmare disorder</td><td>C.</td><td>C.</td><td>✓</td><td>✓</td><td>The sleep disturbance causes <strong>clinically significant distress</strong> or <strong>impairment</strong> in social, occupational, or other important areas of <strong>functioning</strong>.</td><td>The dream experience, or the sleep disturbance produced by awakening from it, causes <strong>clinically significant distress</strong> or <strong>impairment</strong> in social, occupational, or other important areas of <strong>functioning</strong> as indicated by the report of at least one of the following: [...]</td><td>—</td><td>—</td></tr><tr><td>Restless leg syndrome (RLS)</td><td>C.</td><td>C.</td><td>CSC-like</td><td>CSC-like</td><td>The symptoms in <strong>Criterion A</strong> are accompanied by <strong>significant distress</strong> or <strong>impairment</strong> in social, occupational, educational, academic, behavioral, or other important areas of <strong>functioning</strong>.</td><td>The symptoms of RLS cause <strong>concern, distress, sleep disturbance, or impairment</strong> in <strong>mental, physical, social, occupational, educational, behavioral, or other important areas of functioning</strong>.</td><td>—</td><td>—</td></tr></table>

<footnote>* Hypersomnolence disorder for the DSM-5-TR. Sleep disorder labels are those of the ICSD-3-TR, as presented in the transcoding matrix, which harmonizes the wording of sleep disorders across the selected classifications (Supplementary Material 1). Green: CSC; Orange: CSC-like; Red: absence of CSC. A similar wording analysis of all the classifications for four sleep disorders (Chronic insomnia disorder, OSA, Idiopathic hypersomnia and Circadian rhythm sleep disorders-wake disorder) is presented in Supplementary material 3. CSC formulations are in bold; notable wordings presented in the results related section are underlined. AHI: Apnea-Hypopnea Index; CSF: CerebroSpinal Fluid; MSLT: Multiple Sleep Latency Test.</footnote>
<table><caption>**Table 2.** Number of sleep disorder having a Clinical Significance Criteria (CSC), a CSC-like or neither one or the other in the five selected versions of the International Classifications of Sleep Disorders (ICSDs) and the five selected versions of the Sleep disorders section of the Diagnostic and Statistical Manual of Mental Disorders (DSMs).</caption><thead><tr><th></th><th>CSC</th><th>CSC-like</th><th>No CSC & nor CSC-like</th><th>Total number of sleep-wake disorders</th></tr></thead><tbody><tr><td>DSMs <sup>2,8,9,9,10</sup></td><td>20</td><td>8</td><td>9</td><td>37</td></tr><tr><td>ICSDs <sup>1,4-7</sup></td><td>4</td><td>25</td><td>16</td><td>45</td></tr><tr><td>Total number of sleep-wake disorders</td><td>24</td><td>33</td><td>25</td><td>82</td></tr></tbody></table>

The distribution difference between the DSM and the ICSD is significant: X2 (5, N = 82) = 20.8, p = 3e-5. CSC: Clinical Significance Criteria; DSM: Sleep disorders section of the Diagnostic and Statistical Manual of Mental Disorders; ICSD: International Classification of Sleep Disorders.

<table><caption>**Table 3.** Jaccard index of the Clinical Significance Criteria (CSC) between sleep disorder classifications. The detailed information from this Table is graphically presented in **Figure 1-A** and **Figure 1-B**.</caption><thead><tr><th>Overlap between sleep disorder classifications</th><th>Between all selected sleep disorder classifications</th><th>Between the five versions of the DSM <sup>2,8,9,9,10</sup></th><th>Between the five versions of the ICSD <sup>1,4-7</sup></th><th>Between DSM-5-TR and ICSD-3-TR</th></tr></thead><tbody><tr><th>Jaccard Index</th><td>0.24</td><td>0.53</td><td>0.16</td><td>0.40</td></tr></tbody></table>

DSM: Sleep disorders section of the Diagnostic and Statistical Manual of Mental Disorders; ICSD: International Classification of Sleep Disorders.