BigMistakeFl
Actually, drowsy drivers and alcohol related drivers often overlap: (Borrowing from your source of the NHTSA)
"Although sleepiness and alcohol are distinct crash causes, the data also show some evidence of overlap. NHTSA found that drivers had consumed some alcohol in nearly 20 percent of all sleepiness-related, single-vehicle crashes (Wang, Knipling, Goodman, 1996). More than one in three New York State drivers surveyed in drowsy-driving crashes said they had drunk some alcohol (McCartt et al., 1996), and police-reported, fall-asleep crashes had a higher proportion of alcohol involvement than other types of crashes in that State. (New York GTSC Task Force, 1994; New York State Task Force, 1996).
Laboratory studies explain and predict these patterns. Many researchers have shown that sleepiness and alcohol interact, with sleep restriction exacerbating the sedating effects of alcohol, and the combination adversely affecting psychomotor skills to an extent greater than that of sleepiness or alcohol alone (Roehrs et al. 1994; Wilkinson, 1968; Huntley, Centybear, 1974; Peeke et al., 1980). Driving simulation tests specifically show this effect, even with modest reductions in sleep, low alcohol doses, and low blood ethanol concentrations. In a driving simulation study, alcohol levels below the legal driving limit produced a greater number of deviations from the road after 4 hours of sleep than after 8 hours of sleep (Roehrs et al., 1994) (see figure 4). "
So again, we could argue this until the cows come home. Fact is, both are dangerous. I still contend that you will never get lawmakers to lighten up the DUI laws, no matter how many stats we throw at them. You might, however, succeed in increasing penalties and possibly more useful would be more studies about drowsy drivers. Go for it.
