Negative emotions poison the brain just like another poison, alcohol, does. Any amount impairs. The first part of the brain affected, and the most sensitive, is the higher brain. The higher brain is where new data is processesed. It makes judgments, logical assessment and critical analysis possible. Stress/negative emotions immediately impair and quickly shut down this part of the brain. The auto pilot brain takes over. Typically the impaired has NO idea his higher brain is off line. In fact, the impaired usually imagines, incorrectly, they're smarter and more insightful than usual. Mature imbibers realize that despite how they "feel" drunking and thinking don't fix. Instead its time to time out, accept impairment and just be goofy, eat, laugh or whatever doesn't require thinking until the "poison" wears off, they're sober again and their higher brain comes back on line.