Like everyone else a bit difficult to make out all of your post... though that you do not exercise and spend most of your time in front of the tv or on your phone, one of my first suggestions would be to disconnect and go for a nice walk. Not saying it will cure it but that would be the very thing I would try.

I also noticed you didn’t mention your caffeine intake... as I’m sure you’re aware caffeine can cause insomnia and palpitations and feelings of anxiety etc... smoking or nicotine use can also cause the same symptoms, as can suddenly stopping them. So if you were a kick back 10 Red Bull’s a day while starting college and decided wait these are bad for me and dropped to zero the next day that could be causing some issues.

And I also agree the fatalities from insomnia are EXTREMELY rare. And this comes from a life long chronic sufferer of insomnia who once went over a month on less than 8 hours of sleep (total for the whole month plus about 3 days could have been 6 things were a little fuzzy at that point). But still alive and kicking .

But before jumping to pills, consider lifestyle changes, light exercise, balanced diet, get your sunlight exposure at least 15 mins a day, 30 is better, and stay hydrated. If you drink a lot of caffeine slowly cut it back like 1 less caffeinated drink every couple of days to avoid headaches and additional stress, same if you’re a smoker or a vaper, slowly cut back. And if you’ve never sought the energy boost of a caffeinated swallow, maybe trying drinking a cup of tea. (Sounds strange but I find for me sometimes drinking a so called energy drink is the quickest way to send me off to dreamland.)

Wouldn’t even jump to assumption of brain tumor or degeneration just as going without sleep does cause anxiety, forgetfulness, palpitations, tremors and vision problems. And stress increases insomnia symptoms, which never helps when you’re stressing about your insomnia, guaranteed way not to sleep is stressing about not being able to.

As to suffering from nightmares, if they are completely making it impossible to sleep and increasing your anxiety about sleeping because of fear of closing your eyes, IF the lifestyle changes mentioned above do not help to resolve it, seek out a mental health professional, as they could be night terrors which is a completely different beast than a nightmare.

Most importantly, don’t stress, the body can go a very long time on very little sleep. And if it really makes you feel better, I’m sure your doctor wouldn’t mind putting your mind at ease if necessary by giving you and MRI or CT scan.

Though honestly your best bet is to get off the internet diagnosing, take a stroll under the sun around the block, and make sure your diet is balanced with veggies and fruits, meats and grains, and dairy too, and get your 8 glasses of water in you a day. Even if you have to start with baby steps to work around to that. And sometimes understanding that you will still occasionally go without sleep and that is A-ok.