Sleep medicine is undergoing a quiet conceptual revolution. A new commentary in Sleep Medicine Reviews argues that sleep health and sleep disorders are not opposite ends of a single dimension but separate continua that clinicians and researchers must assess independently.
Published online July 13 by an international team led by Runtang Meng (Hangzhou Normal University), the paper proposes a formalized “two-continua model” (TCM) that separates the presence of a sleep disorder from the quality of an individual’s sleep health. The implication is profound: a patient with well-managed obstructive sleep apnea on CPAP can have excellent sleep health, while someone who fails to meet criteria for any formal sleep disorder may still experience chronically poor sleep health that undermines their daily function.
The invisible population
The model’s most actionable insight is the identification of what the authors call the “Q3 population”, individuals with poor sleep health who do not meet diagnostic criteria for any sleep disorder. This group is invisible under traditional diagnostic frameworks. Shift workers, female caregivers, socioeconomically disadvantaged groups, and people living in poor sleep environments may experience structurally constrained sleep opportunity without qualifying for a clinical diagnosis. For these populations, individual sleep hygiene advice is insufficient; the model points toward structural interventions such as policies on shift work, housing, and caregiving support.
Measuring what matters
The authors acknowledge that the plausibility of separating health from disorder varies by condition. It works well for physiologically defined disorders like OSA, where a well-treated patient on CPAP can genuinely have good sleep health. It is more challenging for symptom-based disorders like insomnia, where poor health and disorder symptoms are deeply entangled. The paper argues that the field’s most urgent need is better measurement, not a new conceptual scaffold. It calls for prospective cohorts that measure sleep health domains and disorder-specific features side by side, along with calibrated item banks and formal factor-analytic tests using existing datasets such as MESA Sleep and NHANES.
A complement, not a replacement
Crucially, the title’s second half, “but not beyond sleep medicine”, signals that the TCM is not rejecting diagnosis. Sleep disorders remain clinically categorical for treatment thresholds, coding, and reimbursement. The model adds a second axis for continuous monitoring of intervention effects on function and health. The authors position the two-continua model as a practical framework for expanding sleep medicine’s scope without abandoning its diagnostic foundation.
Source: Meng R, BaHammam AS, Dzierzewski JM, Fan X, Jahrami H, Spruyt K, Ferri R. Beyond diagnosis but not beyond sleep medicine: Clinical and conceptual implications of a two-continua model of sleep health and sleep disorders. Sleep Med Rev. 2026;89:102342. doi:10.1016/j.smrv.2026.102342. PMID: 42468242.