Alcohol withdrawal is the changes the body goes through when a person suddenly stops drinking after prolonged and heavy alcohol use. Symptoms include trembling (shakes), insomnia, anxiety, and other physical and mental symptoms.
Alcohol has a slowing effect (also called a sedating effect or depressant effect) on the brain. In a heavy, long-term drinker, the brain is almost continually exposed to the depressant effect of alcohol. Over time, the brain adjusts its own chemistry to compensate for the effect of the alcohol. It does this by producing naturally stimulating chemicals (such as serotonin or norepinephrine, which is a relative of adrenaline) in larger quantities than normal. If the alcohol is withdrawn suddenly, the brain is like an accelerated vehicle that has lost its brakes. Not surprisingly, most symptoms of withdrawal are symptoms that occur when the brain is overstimulated.
The most dangerous form of alcohol withdrawal occurs in about 1 out of every 20 people who have withdrawal symptoms. This condition is called delirium tremens (also called DTs). In delirium tremens, the brain is not able to smoothly readjust its chemistry after alcohol is stopped. This creates a state of temporary confusion and leads to dangerous changes in the way your brain regulates your circulation and breathing. The body's vital signs such as your heart rate or blood pressure can change dramatically or unpredictably, creating a risk of heart attack, stroke or death.