Inconsistent Use of “Not Better Explained” Criterion Raises Questions in Sleep Disorder Diagnosis

Why It Matters

Inconsistent NBE usage can lead to misdiagnosis, skew prevalence data, and affect treatment decisions, undermining patient care and research reliability. Harmonizing the criterion will improve diagnostic precision across sleep medicine and psychiatry.

Key Takeaways

• ICSD‑3‑TR includes NBE criterion in 9 of 10 disorders.
• DSM‑5‑TR applies NBE to only 7 of 10 disorders.
• Wording varies: DSM‑5‑TR uses multiple phrases, increasing ambiguity.
• Inconsistent NBE use may affect diagnosis rates and treatment choices.

Pulse Analysis

The “Not Better Explained” exclusion rule serves as a safeguard, ensuring that clinicians attribute sleep symptoms to the correct underlying cause rather than to overlapping conditions. In the International Classification of Sleep Disorders (ICSD‑3‑TR), the rule appears in nine of ten examined disorders and is phrased uniformly, reflecting a sleep‑medicine‑centric perspective. By contrast, the Diagnostic and Statistical Manual of Mental Disorders (DSM‑5‑TR) incorporates the criterion in only seven disorders and employs a variety of expressions—such as “not attributable to” and “does not occur exclusively”—which can introduce interpretive uncertainty for practitioners who straddle both domains.

These divergent applications have tangible consequences. When the NBE criterion is omitted or loosely defined, clinicians may over‑diagnose conditions like insomnia or circadian‑rhythm disorders, inflating prevalence estimates and potentially exposing patients to unnecessary pharmacologic interventions. Conversely, overly stringent exclusion can mask comorbidities, delaying appropriate treatment for underlying medical or psychiatric illnesses. The variability also hampers research comparability, as studies using different classification systems may report inconsistent prevalence and treatment outcomes, complicating meta‑analyses and policy formulation.

The authors’ call for harmonization aligns with broader trends toward integrated diagnostic frameworks. Standardizing NBE language and providing clear guidance on handling comorbidities would bridge the gap between sleep‑specific and psychiatric classifications, fostering more accurate diagnoses and consistent care pathways. Such alignment could also streamline training for clinicians, reduce diagnostic errors, and enhance the validity of epidemiological data, ultimately benefiting patients, providers, and health systems alike.