It's not as if forensic scientists are in the line of fire—at least, not in the same way that many of the crime victims they're working on were (too soon?). But the work can be incredibly stressful. Part of the job involves appearing as a witness in court, which usually involves being grilled by eager, energetic attorneys primed to win at all costs.
Outside of court, your livelihood depends on things like murder and mayhem. Crime scenes can be grueling in a sticky, icky, smelly way. Coping with the crime scenes or scenarios can get to be pretty difficult sometimes. Heading to the office every day to consider some of life's bleaker moments can, and probably will, take its toll on the scientist's emotions.
You're going to analyze some pretty gruesome stuff in this line of work. If you're stressed out by glimpsing the dark side of human nature, maybe you should think about doing something else—like baking cookies for a living. We promise we won't judge you.