system
Given the following post, respond as if you're commenting on Reddit:
human
I always feel really depressed and low after a night of drinking. What exactly is alcohol doing to us when we drink, and how long does it take the effects to wear off?
gpt
Psychology major here.

Depressants are a class of drugs that depress or inhibit central nervous system activity. In general, depressants produce drowsiness, sedation, or sleep. Depressants also relieve anxiety and lower inhibitions. All depressant drugs are physically addictive. Also, the effects of depressant drugs are additive, meaning the sedative effects are increased when depressants are combined. 

In the case of Heath Ledger he was found to have multiple prescription drugs in his body, including two kinds of narcotic painkillers, two kinds of anti-anxiety drugs, and two kinds of sleeping medications. None of the legally prescribed medications had been taken in excess. Even so, the combination produced a lethal additive drug effect, depressing his brain's vital life functions to the point that respiratory failure occured.

Generally, it takes about one hour to metabolize the alcohol in one drink, which is defined as 1 ounce of 80-proof spirits, 4 ounces of wine, or 12 ounces of beer. Factors such as body weight, gender, food consumption, and the rate of alcohol consumption also affect blood alcohol levels. A slender person who quickly consumes three drinks on an empty stomach will become more than twice as intoxicated as a heavier person who consumes three drinks with food. Women metabolize alcohol more slowly than men do. If a man and a woman of equal weight consume the same number of drinks, the woman will become more intoxicated.

As far as how alcohol affects the body, it depresses the activity of neurons in the brain. Alcohol impairs cognitive abilities, such as concentration, memory, and speech, and physical abilities, such as muscle coordination and balance. As blood levels of alcohol levels continue to rise, death can occur because the brain's respiratory center can no longer function.

As far as alcohol withdrawal symptoms, it causes *rebound hyperexcitability* in the brain. The severity of the withdrawal symptoms depends on the level of physical dependence. With a low level dependence, withdrawal may involve disrupted sleep, anxiety, and mild tremors, colloquially known as *"the shakes"*. At higher levels of physical dependence on alcohol, withdrawal may involve confusion, hallucinations, and severe tremors or seizures. Collectively, these severe symptoms are sometimes called *delirium tremens* or the the DTs. In cases of extreme physical dependence, withdrawal can cause seizures, convulsions, and even death in the absence of medical supervision.