ABSTRACT
Rumination is a common issue for people with depression (e.g., Nolen-Hoeksema, 1991) and it is also an important issue for people with insomnia (see Carney et al., 2006, 2010, Carney 2013). Rumination is a form of repetitive thinking. The content of the repeated thoughts differs slightly in those with insomnia only versus those with depression; although there is some overlap in content (Carney et al., 2006). In the presence of fatigue, the content tends to focus on somatic symptoms and why (i.e., past-focused thoughts) the symptoms are occurring; inevitably leading to the conclusion that the cause of the fatigue is the previous night's sleep. Such is the type of rumination we see in insomnia but also MDD-I. In contrast, in MDD but not in insomnia only, the thought content in rumination tends to focus on negative aspects of the self. In the context of anxiety, thoughts tend to be future-oriented and catastrophizing (i.e., worry). That is, if someone with insomnia was lying awake, unable to sleep, the content would focus on the future, e.g., “If I don’t get to sleep, I won’t be able to function tomorrow” (e.g., Carney et al., 2010; Harvey, 2002). In each of these scenarios, the thoughts are repetitive and difficult to escape.
