I answer this question in two parts: 1) Time I was aware of what was happening and 2) Times where I probably put myself at enormous risk, but didn't realize it
1) I went to the hospital after vomiting fresh blood, and it turned out I had developed stomach ulcers from chronic use of advil (I had joint problems from weight lifting, and would routinely pop 2 extra strength prior to working out - I did this for close to a year before I had any issues). During the surgery to repair the bleeding ulcers, the lining of my stomach ruptured and I began to bleed out on the table. To make matters worse, I'm a hemopheliac, so any bleeding, much less one that was so severe, poses a risk.
I was told by the doctors after that they had difficulty keeping my vitals stable, and at one point, medical staff went out to tell my mom that I may not make it.
Long story short, I was intensive care for 6 days, and received tons of blood product and clotting agents. It was strange though, I felt fine while in the hospital and asked to be discharged, but doctors said that if I started bleeding again while at home, I would probably die.
2) I have taken an enormous amount of sleeping medication/sedatives due to chronic insomnia, in quantities that I'm pretty sure would kill most people. I have combined 40mg of zopiclone with a packet of OTC sleeping pills (a gram of Diphenhydramine) and a bottle of Nyquil. I have also taken 300mg of codeine at a time, and once combined Seroquil with 40mg of Oxy. Beyond feeling a bit drowsy the next day, there were no ill effects, but it definitely wasn't the safest thing to do.