Computing sleep deficiency.

Sleep deficiency is a major public health concern. Since epidemiological studies play an important role in public health evaluations, this theoretical paper pursues answers to the question: 'How can we compute sleep deficiency as informative measures of exposures or doses in observational research?' Starting from the social jetlag concept and based on the chronodisruption rationale, we illustrate and discuss five approaches (one established and four untested, each with unique strengths and limitations) to quantify sleep deficiency by focusing on the timing and duration of sleep. Hitherto, social jetlag and chronodisruption rationale were neither explicitly proposed nor developed as assessments of sleep deficiency but, as we suggest, could potentially be utilized to this end. This first foray into computing sleep deficiency in epidemiological studies makes clear that laboratory, field and epidemiological collaboration is pre-requisite to elucidating potential (co-)causal roles of sleep deficiency in disease endpoints.