and feelings that usually happen involuntarily in the mind during specific stages of sleep.

The content and goal of dreams are not fully understood, although they have been a topic of scientific, philosophical and religious interest throughout recorded history.

Dream interpretation is the attempt at getting meaning from dreams and searching for an underlying message.

Dreams mainly occur in the rapid-eye movement (REM) stage of sleep—when brain activity is high and resembles that of being awake.

REM sleep is revealed by continuous movements of the eyes during sleep.

At times, dreams may occur during other stages of sleep.

The length of a dream can vary; they may last for a few seconds, or approximately 20–30 minutes.