A lucid dream occurs when the dreamer is aware of the events happening during the dream. Studies suggest that a person can learn to lucid dream by some simple steps outlined in this video. Lucid dreams are strongly associated with REM sleep. REM sleep is more abundant just before being awake. Other ways to practice are to keep a dream journal or practice reality checks like turning on a light switch.
Nina Sen is a frequent contributor to Live Science’s Life’s Little Mysteries series: an exploration and explanation of our world’s phenomena, both natural and man-made. She also writes astronomy photo stories for Live Science's sister site Space.com.