Then the journal could help you notice the problem and take action sooner.
I've had a lot of stress at work. Here's how I dealt with it:
I was once working for a boss who was really infuriating to deal with. To prevent myself from exploding at him, I would take a break, step outside in the beautiful sunlight, put in my earbuds, turn on some good music, and run. I channeled my frustration into exercise. I'd especially make a habit of doing this just before I ate lunch, which would stimulate muscle growth and make me happier and healthier. Somehow that stressful job got me into great shape.
I was once working at a place where all the policies were dysfunctional and things were constantly on fire. I dealt with this by pulling out my phone and using the Headspace app to think about nothing for a moment and calm myself down. When I got back to the work, I'd put on some "focus" music (music for programming, studying, etc) that would help me maintain my calm mood when implementing the fixes. I learned to distance myself from the problem and get people to talk to each other to work it out instead of having proxy arguments on other peoples' behalf.
I've had some pretty bad sleep problems as well. I got into the habit of playing videogames late at night, which really destroyed my sleep. It's really hard to sleep right after staring at bright screens and experiencing intense action. Now I have F.Lux or Night Shift enabled on all my machines and I avoid playing console games at night without wearing yellow safety glasses. Also, I've started adding concentrated lake water to my drinking water since a magnesium deficiency can make it difficult to sleep.
For depression, perhaps learn about Taoism?
If you really can't cope with the job, quit. It'll be even more stressful to try to find a new job while you're already working one. You can search for a new job using TripleByte, which saves a lot of time since you just have to do one coding test instead of 20.
Hope this helps. Good luck.