title: Sleep and satisfaction in 8- and 12-h forward-rotating shift systems: Industrial employees prefer 12-h shifts.
abstract: Twelve-hour shift systems have become more popular in industry. Survey data of shift length, shift rotation speed, self-rated sleep, satisfaction and perceived health were investigated for the associations among 599 predominantly male Finnish industrial employees. The studied forward-rotating shift systems were 12-h fast (12fast, DDNN------, n = 268), 8-h fast (8fast, MMEENN----, n = 161) and 8-h slow (8slow, MMMM-EEEE-NNNN, n = 170). Satisfaction with shift system differed between the groups (p < 0.01) after controlling for age, gender, shift work experience and self-rated stress. In the 12fast, 98% of employees were satisfied with their shift system (75% 8fast, 54% 8slow). Negative effects on sleep and alertness were rare (8%) in the 12fast group (53% 8fast, 66% 8 slow, p < 0.01) and self-reported sleep difficulties were less frequent than in the 8fast and 8slow groups (8%, 27%, 41%, respectively, p < 0.01). The self-reported average sleep duration (12fast 7:50, 8fast 7:24, 8slow 7:15, p < 0.01), and shift-specific sleep before and between morning shifts and after first night shift were longer in the 12fast group. Perceived negative effects of the current shift system on general health (12fast 4%, 8fast 30%, 8slow 41%, p < 0.001) and work-life balance (12fast 8%, 8fast 52%, 8slow 63%, p < 0.001) differed strongly between the groups. In conclusion, the perceived effects of shift work were dependent on both shift length and shift rotation speed: employees in the 12-h rapidly forward-rotating shift system were most satisfied, perceived better work-life balance and slept better than the employees in the 8fast or especially the employees in the 8-h slowly rotating systems.
authors.affiliation: a Modern Work and Leadership , Finnish Institute of Occupational Health , Helsinki , Finland.
authors.forename: Kati
authors.initials: K
authors.lastname: Karhula
authors.affiliation: a Modern Work and Leadership , Finnish Institute of Occupational Health , Helsinki , Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Härmä
authors.affiliation: a Modern Work and Leadership , Finnish Institute of Occupational Health , Helsinki , Finland.
authors.forename: Annina
authors.initials: A
authors.lastname: Ropponen
authors.affiliation: a Modern Work and Leadership , Finnish Institute of Occupational Health , Helsinki , Finland.
authors.forename: Tarja
authors.initials: T
authors.lastname: Hakola
authors.affiliation: a Modern Work and Leadership , Finnish Institute of Occupational Health , Helsinki , Finland.|b Agora Center , University of Jyväskylä , Jyväskylä , Finland.
authors.forename: Mikael
authors.initials: M
authors.lastname: Sallinen
authors.affiliation: a Modern Work and Leadership , Finnish Institute of Occupational Health , Helsinki , Finland.|c Institute of Behavioural Sciences , University of Helsinki , Helsinki , Finland.
authors.forename: Sampsa
authors.initials: S
authors.lastname: Puttonen
mesh_terms: D000293:Adolescent; D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D005387:Finland; D006801:Humans; D008297:Male; D008875:Middle Aged; D016272:Occupational Health / Q000706:statistics & numerical data*; D010549:Personal Satisfaction; D010561:Personnel Staffing and Scheduling; D012890:Sleep / Q000502:physiology*; D007319:Sleep Initiation and Maintenance Disorders / Q000503:physiopathology; D011795:Surveys and Questionnaires; D013997:Time Factors; D014940:Work Schedule Tolerance / Q000502:physiology*; D055815:Young Adult
keywords: Night work; shift schedules; sleep difficulties; work–life balance