Although the DSM-5 and the ICSD-3 do not discriminate among insomnia types or subtypes anymore, it appears that some specific insomnia phenotypes remain important to study. One of them is the object of the present paper: insomnia with short sleep duration. Since Vgontzas and colleagues (1) put forward a heuristic model of two insomnia phenotypes based on objective sleep duration, they have suggested that insomnia with short sleep duration is the most severe biological phenotype of insomnia, and research in this area has been blooming. The Penn State group has studied the impact of this phenotype on adolescents and its association with depression risks and inflammation (2-4). A recent review by Fernandez-Mandoza (5) also suggested that besides increased physiological hyperarousal and cardiometabolic and neuropsychiatric risks, insomnia with short sleep duration may even respond differently to treatment compared to other insomnia phenotypes.