Abstract
STUDY OBJECTIVES: Chronic insomnia is a prevalent sleep disorder that negatively affects daytime functioning and confers risk for the future development of psychiatric disorder. Patients with insomnia often report problems with emotion regulation and impaired social interactions. Moreover, experimental sleep loss in healthy adults is associated with altered reactivity to and interpretation of emotional information. In the current study, we investigated socioemotional processing in patients with chronic insomnia disorder relative to healthy good sleepers. DESIGN: Between-groups comparison. SETTING: Sleep Research Laboratory. PARTICIPANTS: Patients with well-defined psychophysiological insomnia (PI; n = 16), free from psychiatric disorder, and an age- and sex-matched control group of good sleepers (GS; n = 15). INTERVENTIONS: N/A. MEASUREMENT AND RESULTS: All participants completed a facial expression recognition task, between 18:00 and 19:00, requiring participants to categorize and rate the intensity of four emotional expression categories: anger, fear, happiness, and sadness. People with PI did not differ from GS with respect to categorization of facial expressions. However, in terms of intensity judgements, across all emotion categories, patients tended to rate faces as less emotionally intense (Cohen's d = 0.70). Specifically, they rated expressions displaying sadness and fear as significantly less emotionally intense than healthy GS (both P < 0.05; Cohen's d = 0.77 and 0.89, respectively). Measures of sleepiness (Psychomotor Vigilance Test, Karolinska Sleepiness Scale) or self-reported sleep were not reliably associated with emotional intensity ratings. However, anxiety and depression were negatively related to intensity ratings. CONCLUSION: For the first time we show that chronic insomnia is associated with reduced ratings of emotion intensity for face expressions displaying sadness and fear. Further work is required to elucidate possible mechanisms and pathways underlying insomnia-related emotional impairment.