Sleep duration (SD) is a predictor of an individual's health
status. Insufficient sleep is a common characteristic in our
24 h/7 days a week modern society and can lead to metabolic
dysfunction, obesity, hypertension, heart attack, stroke [1]
and coronary heart disease [2]. On the other hand, there is
conflicting evidence that we are not as deprived of sleep as
we think we are; because in some countries, people are
sleeping more [3,4].