I get nightmares very frequently since my concussion happened. In most nights I wake up around 4 or 5 am and start to struggle to fall asleep again(I sleep good until that point). It takes about 3 or 4 hours until I sleep in again. Then the sleep pattern gets very strange. I wake up every 15-30 minutes and only for a few seconds. During this time i get numerous nightmares, which do not always result in waking up.
All in all this strange sleep summarizes to about 3 hours. During the day i get no sleep, no matter how tired I am

My question is now how do nightmares effect the brain? Nightmares raise the stress level and the output of adrenaline and cortisol. Both stress hormones are neurotransmitters and harm the brain cells(at least that's what I've read so far). If this is true, i will abstain from the bad sleep occurring after 4 am and stay awake.