title: Shiftwork locus of control, situational and behavioural effects on sleepiness and fatigue in shiftworkers.
abstract: A number of situational and behavioural individual differences moderate the impact of shift and night work. The aims of this study were to identify individual differences correlates of sleep and fatigue-related shiftwork outcomes and examine their potential relative causal impact. Power company shiftworkers completed a questionnaire that measured age/experience, number of dependents, shiftwork locus of control, morningness-eveningness, workload and sleep/health-related behaviours. Shiftwork sleep and fatigue outcome variables were also measured. Hierarchical multiple regression was used to examine predictive contributions of the individual difference variables and to generate path coefficients from situational and psychological predictors through behavioural variables to the outcome variables. Shiftwork-specific internality showed the most systematic significant causal relationships with sleep and fatigue outcomes. While not having as strong a direct causal influence on sleep and fatigue outcomes as internality, the other predictors did show more significant causal effects upon sleep-related behaviours than did internality. Behavioural variables made little contribution to the total causal effects of the predictors on the outcome variables. The results suggest control beliefs to be a moderating factor in shiftwork exposure and the potential utility of this construct in aiding more effective targeting of interventions.
authors.affiliation: Shiftwork Research Group, Institute of Psychological Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Lawrence
authors.initials: L
authors.lastname: Smith
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tanigawa
authors.forename: Masaya
authors.initials: M
authors.lastname: Takahashi
authors.forename: Keiko
authors.initials: K
authors.lastname: Mutou
authors.forename: Naoko
authors.initials: N
authors.lastname: Tachibana
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Kage
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Iso
mesh_terms: D000328:Adult; D005221:Fatigue / Q000209:etiology / Q000523:psychology*; D015438:Health Behavior; D006801:Humans; D007389:Internal-External Control; D007564:Japan; D008297:Male; D010561:Personnel Staffing and Scheduling; D011210:Power Plants; D012307:Risk Factors; D012647:Self-Assessment; D020178:Sleep Disorders, Circadian Rhythm / Q000209:etiology / Q000523:psychology*; D011795:Surveys and Questionnaires; D013995:Time; D014940:Work Schedule Tolerance / Q000523:psychology*; D000078329:Workforce; D016526:Workload / Q000523:psychology