http://goo.gl/nxhtBo
According to the authors, repetitive negative thinking is "defined as an abstract, perseverative, negative focus on one's problems and experiences that is difficult to control."
Individuals who have such thoughts tend to worry too much about the future or the past, and they experience intrusive thoughts that can be bothersome.
Nota and Coles say individuals who have such thoughts typically suffer from generalized anxiety disorder, major depressive disorder, post-traumatic stress disorder, compulsive disorder or social anxiety disorder. Likewise, these individuals typically experience sleep problems.
Results showed that the students who slept for shorter periods and went to bed later experienced more repetitive negative thoughts, compared with those who slept for longer periods and went to bed earlier.
Additionally, the students who identified as "evening types" also experienced more repetitive negative thoughts.