Are cognitive variables that maintain insomnia also involved in shift work disorder

OBJECTIVE: Shift Work Disorder (SWD) is explained mainly by a misalignment between the sleep schedule and the circadian rhythm. However, the possible role of cognitive variables in maintaining SWD remains unknown. Therefore, the objective of this study is to evaluate whether cognitive variables known to maintain insomnia in day workers might also be involved in perpetuating SWD. DESIGN: Cross-sectional. SETTING: Sleep laboratory. PARTICIPANTS: Twenty-five shift workers diagnosed with SWD (84% females; mean age = 35.9) and 22 shift workers who are good sleepers (91% females; mean age = 34.1). MEASUREMENTS: The participants completed a sleep diary for two weeks, answered questionnaires, and underwent the Harvey's semistructured interview and the catastrophizing procedure. Data from the catastrophizing procedure underwent a content analysis. RESULTS: Compared with good sleepers, shift workers with SWD reported experiencing more thoughts that keep them awake, more presleep cognitive arousal, more dysfunctional beliefs related to worries and helplessness, and more selective attention toward worries and noises. However, the two groups did not differ on the tendency to catastrophize about difficulties falling asleep. Furthermore, 12 catastrophizing themes were identified in the entire sample, the most frequently endorsed being "sleepiness and energy" and "performance at work." CONCLUSIONS: The results suggest that cognitive variables may play a role in maintaining SWD. Finally, worries that interfere with sleep in shift workers are related to their work context.