Short answers, pulled from the story.
Humans spend more than two hours dreaming per night, and each individual dream lasts around 5-20 minutes. Dreams occur mainly during the rapid-eye movement, or REM, stage of sleep, though they also occur during non-REM sleep.
Anxiety is the most common emotion experienced in dreams, according to Calvin S. Hall's study. Other emotions include abandonment, anger, fear, joy, and happiness, but negative emotions are far more common than positive ones.
A lucid dream is any dream during which the dreamer knows they are dreaming. Psychologist Keith Hearne first recorded a communication from a lucid dream on the 12th of April 1975, when subject Alan Worsley moved his eyes left and right on agreement after becoming lucid.
Yes. In visitation dreams described in Mesopotamia and Ancient Egypt, a deity or prominent forebear commanded the dreamer to take specific actions. Gudea, king of the Sumerian city-state of Lagash who reigned around 2144-2124 BCE, rebuilt the temple of Ningirsu because a dream told him to.
Dreams figure prominently in major world religions. Most dreams in the Bible appear in the Book of Genesis, including Jacob's dream of a ladder stretching from Earth to Heaven. In Islam, dream interpretation became the only path to revelation from God after the death of the last prophet, Muhammad.
The scientific study of dreams is called oneirology. Science does not know where in the brain dreams originate, whether there is a single origin or multiple regions involved, or what the purpose of dreaming is.