[Cognitive and emotional alterations in chronic insomnia]

Little is known about the cognitive and emotional alterations associated with chronic insomnia.

After reviewing the aetiology and pathophysiology of chronic insomnia, taking into account the patient's vulnerability and its inheritability, this study reports on the knowledge currently held about the cognitive deficits and emotional alterations observed in patients with chronic insomnia.

Most aetiological models include factors that predispose an individual to insomnia, as well as precipitating and maintaining it. Predisposing factors can be of a biological or psychosocial nature. One predisposing factor that plays an important role is the vulnerability to insomnia, which is related to a non-adaptive way of coping with stress (focused on the emotion rather than on the problem) and the internalisation of negative emotions, which favours a state of physiological, cognitive and emotional hyperactivation that disrupts sleep and may lead to insomnia. This vulnerability is largely hereditary. Two phenotypes, based on the objective duration of sleep, have been described, the difference between them being the severity of the disorder. Insomniacs with an objective sleep time below six hours present significant cognitive deficits. These become manifest in tasks that require a large number of cognitive resources, complex attention tasks, changes in the focus of attention, the process of consolidation of memory during sleep, and working memory. These data suggest the existence of a prefrontal dysfunction. Comorbidity between insomnia and anxiety-depression is high. The anxiety-depression triggered by the internalisation of emotions predisposes the individual to insomnia and this, in turn, intensifies the depression.