Of all the dreams humans may experience in deep sleep, a recurring dream may feel the most mysterious — and in some cases, the most terrifying. Dreams can vary greatly from person to person; the American Sleep Association notes that people, on average, experience three to five dreams every night, usually lasting between 20 and 30 minutes in length. Because dreams tend to form when humans are in their deepest sleep (a.k.a REM sleep, when your brain recharges overnight!), it is not uncommon to have sweet, pleasant dreams right before confusing ones or even scary nightmares.
https://www.goodhousekeeping.com/author/224431/Zee-Krstic/
Mws R Writings 