Studies have shown that in healthy people, acute high alcohol doses disturb sleep. Alcohol interrupts your sleep patterns by compromising the body’s ability to return to homeostasis, its normal operating functions. Caffeine, one of the most dangerous legal drugs, dehydrates you. If you don’t want to wake up with a headache, dry mouth, bad breath, and digestive problems, drink water. When lacking it, the body restricts airways as a self-defense mechanism to preserve whatever water it has left.