If you've ever had a nightmare, you're in good company. Almost everyone gets them once in a while - adults, as well as kids. A nightmare is a bad dream. It can may make you feel scared, anxious, or upset, but nightmares are not real and can't harm you.
While you sleep, your brain doesn't just turn off. It goes through several sleep stages, including REM, or Rapid Eye Movement, sleep. Why do they call it that? Because during this stage of sleep, your eyes move back and forth under your closed eyelids. During REM sleep, you have dreams and sometimes those dreams can be scary or upsetting.
About every 90 minutes your brain switches between non-REM sleep and REM sleep. The amount of time spent in REM sleep increases with each sleep cycle through the night. The longest periods of REM sleep occur towards morning. If you wake during this REM stage, it is easier for you to remember what you were dreaming about. That's why your most vivid dreams - and nightmares - occur in the early morning hours.
"my friend recently had nightmares a few days ago, it was so scary but i can not explain further, hope he's reading this to tell us more."