The Sleep Opportunity, Need and Ability (SONA) Theory

'How much sleep does one need?' is a critical question that has been difficult to answer. The long history of sleep research has culminated in population-derived normative values of 7 to 9 h of sleep per night to avoid dysfunction. Such a wide range is sufficiently large that one cannot know what is required for any given individual. 'Sleep need' cannot currently be directly measured, might not be represented by one number (given the multiple functions that sleep subserves), and likely varies from individual-to-individual and from day-to-day. This said, the concept should be embraced and can be considered alongside more easily operationalised and routinely measured constructs of 'sleep opportunity' (e.g., time in bed) and 'sleep ability' (i.e., the obtained sleep, such as sleep duration). Considering the dynamics of all three constructs together may drive greater understanding about sleep health, sleep insufficiency, and sleep disorder pathology. In this article, we describe a new theory called Sleep Opportunity, Need, and Ability and provide a rationale for why this theory has both theoretical and clinical value.