One of the largest causes of death - Suicide. Sadly it's not mentioned much in the media. Even worse is the medicine they hand out to deal with depression. I've seen plenty of people lose their shit on anti-depressants and only be told to take stronger medication. Pharmaceutical companies really need to be more careful in their research before handing out anti-depressant related medication - anything that fucks with your dopamine unnaturally should be treated with precaution, yet docs will give it to you for merely saying you're upset about life...
I've found that the greatest cure to feeling upset or depressed is to actually start eating healthy food, exercise, get outside and embrace the sun for its Vitamin D. No joke. The amount of people who take the sun and good food for granted is absolutely insane. I feel bad for people who have to spend all day in an office avoiding the sun. Though they might enjoy the aircon, the sun is vital to feeling emotionally stable. This is perhaps why Greenland has one of the highest suicide rates in the world - because it is dark for most of the year over there.