Sometimes dreams involve highly emotional content that disturbs the dreamer. Fear is the most common emotion involved. But these dreams also may involve anger, disgust, embarrassment, or other negative feelings.

These are some of the most common themes of bad dreams:

 
• Being in danger  
• Being alone or trapped  
• Facing natural forces

These dreams are disturbing because they seem real. They tend to become more intense as they unfold. The memory of a bad dream can bother you as you go about your day.

A bad dream that causes you to wake from your sleep is called a “nightmare.” A nightmare disorder may develop if you have repeated nightmares that cause emotional distress. Nightmares almost always occur during rapid eye movement (REM) sleep, or “stage R sleep.”

Research shows that ongoing nightmares can have negative health effects. Studies have linked nightmares to these problems:

 
• Disturbed sleep  
• Sleep avoidance  
• Daytime anxiety  
• Depression  
• Suicide

Like other dreams, nightmares tend to reflect your daytime concerns. They occur more often when life events cause you to feel anxious or stressed. Nightmares often occur as a result of a traumatic event. In the dream you may experience the traumatic event all over again.

Nightmares are more common in children. Women also are more likely to report them than men. It is unclear if men have fewer nightmares, or if they simply recall and describe them less.
Sources

_{Kryger M, Roth T, Dement W, editors. Principles and practices of sleep medicine. 4th ed. Philadelphia: Saunders; 2005.}

Lee-Chiong TL, editor. Sleep: a comprehensive handbook. Hoboken, N.J.: John Wiley & Sons; 2006.