Many people that have sleep disorders have brown hair. Many people that have sleep disorders drive Fords. Many people that have sleep disorders like asparagus. All technically true, but all very misleading. Many sleep disorders have nothing to do with weight. The only one I can grab off the top of my head that does is apnea, and that's limited to Obstructive Sleep Apnea (admittedly, the most common sleep disorder that I know of). Alcohol use, smoking, and other factors also contribute to O.S.A. Central Sleep Apnea is like the old joke..."forgot how to breathe" (there is fault with the signal from the brain, or with its delivery). Many overweight people have been misdiagnosed with narcolepsy, only to find that what they really have is severe Obstructive Sleep Apnea. So severe that they fall asleep during waking hours like a narcoleptic; instantly, and at any given moment. There are many, many, many different types of sleep disorders.