When You Don't Have Chronotype Data: Sleep Questionnaires as a Circadian Window

This letter proposes a strategy for deriving proxies of circadian preferences from self-reported sleep timing data. The potential of such an approach to enhance epidemiological research is discussed, and its feasibility is demonstrated using sleep onset, sleep offset, and sleep midpoint derived from the Pittsburgh Sleep Quality Index, based on previously collected data from a cohort of Italian university students.