The actual cause of hangovers is unknown. We know that a hangover is a result from drinking too much alcohol, but why does alcohol cause hangovers? Some of the symptoms of a hangover include headache, fatigue, nausea, sweating, confusion, stomach issues. Many people believe that hangovers are a result of dehydration, given the fact that when you drink a lot of alcohol you have to pee a lot, and you're probably not drinking a lot of water. However, many studies have proven that there is no correlation between high levels of the hormones associated with dehydration and the severity of a hangover. It's likely that dehydration causes some of the symptoms of a hangover, but dehydration is not the direct cause of a hangover. 
Another theory as to where hangovers come from is that high levels of alcohol interfere with your body's natural chemical balance. In order to process high amount of alcohol, your body has to convert the enzyme NAD+ into an alternate form NADH. When you have too much NADH and not enough NAD+, your cells aren’t capable of doing a lot of things they normally do like absorbing glucose or regulating electrolyte levels. However this has also been shot down by a study that found when people are drunk they don’t necessarily have lower electrolyte or glucose levels. 
The most compelling theory so far is that hangovers result from a release of the toxic compound Acetaldehyde. Acetaldehyde is the first byproduct of processing alcohol, and can be 10-30x more toxic than alcohol itself. In a controlled study, Acetaldehyde has been proven to cause all of the same symptoms as a hangover.
Hangovers have also been proven to be slightly genetic. Certain people don't experience hangovers as much as others. Sometimes, this is due to race. It is common for women to experience more severe hangovers than men, but that can be explained by the fact that women generally weigh less than men. Age also plays a role in hangover severity, but that can be due to the fact that as you get older you are less likely to binge drink, or your body is becoming more and more used to alcohol.

Binge drinking almost always leads to a severe hangover, and many college students binge drink. In fact, 80% of college students say they drink on a regular basis. Many college students binge drink because they work all week then the second they get out of class, drink in huge amounts. Hangovers can make you extremely sick, and sometimes too sick to go out or work. Some things you can do to relieve a hangover are drinking water or sports drinks, eating light, and taking pain relievers. 

As someone who is going to college in a couple of months, I want to be prepared for this new lifestyle. I want to be educated on why so many college students get sick when they party, and how to help myself and my friends be safe.