The stage of sleep you're in might have something to do with your dreams, and people tend to dream more during rapid-eye movement (REM) sleep , the stage of sleep when your brain is very awake, says Shelby Harris, PsyD, director of behavioural sleep medicine at the Sleep-Wake Disorders Center at Montefiore Medical Center . Dreaming during REM is sort of "a way for your brain to figure out what to remember and file away in the filing cabinet, and what to shred and forget," Dr. Harris says. "This is why dreams tend to be jumbled at times, but also so literal — they're truly ways for us to consolidate emotions and memories, and to figure out what to remember and what to forget." Waking up during REM sleep can make your dream feel even more realistic, according to Dr. Breus.