Sleep disorders and mood disorders. The association is well known and firm, as indicated by a new research published in Journal of Behavior Therapy and Experimental Psychiatry. Those who sleep less than eight hours a night – the authors have seen – find it more difficult to keep away negative, intrusive and restless thoughts, all traits typical of people with psychological disorders such as anxiety and depression. We discuss this with Dr. Vincenzo Tullo, neurologist and Head of the Humanitas migraine outpatient clinic.
The two researchers, from Binghamton University in New York (United States), involved 52 adults with high levels of repetitive negative thinking in the study. The concept of “repetitive negative thinking” is a concept recently introduced in literature that identifies a process through which an individual focuses his or her attention on problems and experiences in an uncontrollable way.
This form of thought is associated with various symptoms of anxiety or depressive disorders, such as fear about future events or the havoc over past events, researchers point out. Moreover, the people who manifest these symptoms are often affected by sleep disorders and circadian rhythm disorders. If this form of thought is increased, it may be difficult to move attention away from information that can provoke a negative emotional reaction. Thus, it can help to increase repetitive negative thinking. The participants in the study were shown images with the aim of eliciting an emotional response. In front of these stimuli their attention was detected through eye movement.
At the end of the research, the two scientists saw that alterations in sleep, particularly the difficulty of falling asleep, were related to the difficulty of diverting one’s attention from information that could stimulate a negative emotional reaction. Poor rest could therefore help to keep negative thoughts and remorse “alive” and to ensure that they undermine individuals’ quality of life. As the authors of the research remind us, under normal conditions an individual is able to receive negative information but continue with their day. The opposite of what participants showed during the tests.
In conclusion, the data suggests that sleep disorders may be associated with a specific impact on the cognitive resources needed to control attention and divert it from negative emotional information. However, the study, as the scientists themselves remind us, has some limitations. A cause and effect relationship between sleep and attention cannot be inferred from this type of study. The work was also conducted without a control group that could have indicated how the relationship between insomnia, attention and emotional reaction could not be exclusive to subjects with repetitive negative thinking. Therefore, further research is needed on the correlation between insomnia and this relevant form of thought in various psychological disorders.
Depression, anxiety and brooding
The relationship between sleep disorders and psychological disorders is close: “Sleep disorders affect about 90% of depressed subjects. Depression – explains Dr. Tullo – can be associated with hypersomnia and excessive daytime sleepiness as well as insomnia and thus a decrease in the quality and quantity of sleep. Depressed subjects sleep for a few hours and wake up very early, often in distress. Sleep latency is longer and the amount of slow wave sleep (restful sleep) is reduced by about 1/3 compared to normal subjects”.
“Furthermore, the relationship between depression and insomnia is twofold in the sense that insomnia is not only a typical symptom of depression but it may also be a risk factor for the onset of depression”.
“Depression and anxiety are often accompanied by a mental phenomenon, brooding, which contributes to the maintenance and aggravation of these two disorders. It is characterized by repetitive and uncontrollable thoughts focused on negative content of events that may happen in the future. Brooding can have harmful effects on physical and mental health; chronic remorse can lead to disabling psycho-physical symptoms such as insomnia, restlessness, headache, irritability, nausea and lack of attention and concentration,” the specialist concludes.