As an old Irish proverb states, "The beginning of health is sleep." Sleep experts define healthy sleep as the quantity and quality of sleep required for maintaining optimal alertness during waking hours. Sleep is biologically imperative, though Americans try to get by with less and less. This practice, however, has potentially severe consequences. The effects of sleepiness and fatigue are impaired reaction time, judgment, vision, information processing, logical reasoning, verbal ability, short-term memory, and lowered decision-making ability. Alcohol and lack of sleep have similar negative effects on human performance.