According to CBS News, a study published in the journal Sleep identified three risk factors which may reveal why some people experience recurring bad dreams. People with depression, insomnia and exhaustion seem to be at greater risk for experiencing nightmares. out of more than 13,000 people surveyed, nightmares were significantly more common among people with a “negative attitude toward self” and people with severe symptoms of depression. People suffering from insomnia and fatigue were also more prone to having bad dreams, 17 percent of the insomniacs surveyed reported frequent nightmares. The research does not prove that these conditions actually caused nightmares, but it is possible that the bad dreams are a result of poor sleep quality.