A two-continua model of sleep health and sleep disorders: Why framework proliferation is a feature

Multi-dimensional sleep health (MDSH) frameworks emerged in the 2010s to articulate positive sleep health beyond the absence of sleep disorders. Meng et al. (2026) [1] provide the first systematic review directly comparing the two leading instruments, the Ru-SATED scale (Buysse, 2014; Ravyts et al., 2021) [2, 3] and the Sleep Health Index (SHI) (Knutson et al., 2017) [4], and surface two unresolved tensions: a conceptual question (what is the relationship between sleep health and sleep disorders?) and an operational question (will sleep science converge on a single MDSH framework?). This perspective elaborates Meng et al.'s brief observation that MDSH is orthogonal to sleep disorders into a Two-Continua Model (TCM), drawing on the dual-continua model of mental health. The TCM defines a sleep disorder continuum (X-axis) and an orthogonal sleep health continuum (Y-axis), generating a four-quadrant typology. Implications: the typology identifies under-attended populations for surveillance; MDSH complements rather than replaces disorder-focused science; joint-axis modeling integrating disorder and health information yields more powerfully predictive frameworks; and a proliferation of tailored MDSH frameworks is a feature of a maturing research program, not a defect.