INTRODUCTION
Short sleep duration and insufficient sleep are common in the general population and have many effects on the biological and physiological processes in a body, causing metabolic dysfunction [1–8]. Several epidemiologic studies have documented that self-reported short and/or long sleep duration and insufficient sleep due to sleep difficulties are associated with adverse health outcomes including obesity, cardiovascular disease, and mortality [6, 9–12], but remarkably few studies have investigated individual differences in both response to insufficient sleep and physiologic sleep need and their association with adverse health outcomes [6]. There are likely natural short sleepers or natural long sleepers who have lower/longer basal sleep need and, hence, would not suffer adverse consequences. However, it is uncertain whether the established negative effects of sleep duration (particularly short sleep) on cardiometabolic health relate at least partially to unmet sleep need, in addition to sleep duration.