I think overworking is destroying my brain

I’m in a huge rut. I’m in my third year of engineering school and I’ve been working full time since I was a senior in high school. At first, I was stressed out all the time but I got used to it. But now, I feel like it’s having long term consequences. I’m at work/school from 4am-7pm 5 days a week. I just started a new job a few months ago and I’m still getting trained, so I’m constantly using my brain pretty much all day. I can’t retain any information anymore. It takes so long to think of the next thing to say in a conversation and I’m always forgetting things that I learned literally the day before. I get a decent amount of sleep during the week, and I try to eat as healthy as I can, and I really have no clue what other changes I can make to stop having such bad brain fog. In my situation I don’t really have a choice of doing less school/less work because I am financially independent from my parents and don’t get financial aid. I already take classes over the summer to lighten the work load over the school year, and I changed my major to something a little less rigorous to keep up. What else can I do to stop ruining my brain??