In lucid dreams, the dreamer is aware of the fact that he or she is dreaming, and often can manipulate or control the dream as it unfolds. 

Studies have found that lucid dreamers displayed significantly higher brain wave...

Recurring dreams are dreams that re-appear with some pattern of regularity. 

Studies suggest that recurring dreams may contain more threatening content than regular dreams. Research suggests links between recurring dream...

Night terrors are very intense episodes of fright during dreams. These frightening episodes are often accompanied by screaming or yelling, as well as by physical movement such as leaping out of bed or flailing in panic. 

Research suggests that sleep terrors occur during non-REM sleep...

Another function of dreaming appears to be processing and coming to terms with traumatic events. Grief, fear, loss, abandonment, even physical pain are all emotions and experiences that often replay themselves in dreams.