Psychophysiological reactivity to sleep-related emotional stimuli in people with insomnia: An fMRI study

Insomnia is reported in most psychiatric disorders and, at least with respect to depression, a meta-analysis of longitudinal data has shown that people with insomnia have a two-fold risk of developing depression, compared to good sleepers [1]. A recent hypothesis has proposed that sleep disturbances consistent with symptoms of insomnia might contribute to the development and the maintenance of psychopathology in general [2]. However, so far, the psychophysiological mechanisms which could explain the association of insomnia with other psychiatric conditions are not yet fully understood. Heightened emotionality has been proposed to be a possible mediating factor; however there is a surprising lack of studies using physiological indices. In one study, we evaluated brain reactivity to emotional stimuli in people with primary insomnia and in good sleepers. Patients with primary insomnia (n = 22) and healthy controls (n = 40) were presented with different blocks of neutral, negative, and sleep-related negative pictures during an fMRI task. Neutral and negative pictures were taken from the International Affective Picture System (IAPS), while sleep-related negative pictures were previously validated. Stimuli were matched for valence and arousal levels. All participants previously underwent a clinical interview and two consecutive nights of polysomnographic recordings in order to exclude those with other psychiatric or sleep disorder. Data suggest an amplified hyper-limbic response by the amygdala to negative emotional stimuli related to sleep in patients with primary insomnia as compared to healthy good sleepers. According to recent cognitive models of insomnia [3–5], a selective attention to internal/external sleep-related cues is involved in the aetiology and maintenance of poor sleep. The results of this study suggest that the phenomenon of “sleep-related attentional bias” described in insomnia is associated with intense negative emotions. Clinical implications of the present findings, which need confirmation by further investigation, suggest that adding an emotional regulation component to standard therapy for insomnia, especially considering the time of the day associated with sleeping, might be effective to ameliorate the disorder. In addition, clinical attention to emotional processes in patients with insomnia could benefit to prevent the establishment of comorbid psychiatric conditions. Baglioni et al. (2011). Journal of Affective Disorders : 135: 10–9; Harvey et al. (2011). Clinical Psychology Review : 31: 225–35. Espie et al. (2006). Sleep Medicine Reviews : 10: 215–45. Harvey (2002). Behaviour Research and Therapy : 40: 869–93. Riemann et al. (2010). Sleep Medicine Reviews : 14: 19–31.