Table 1.
Author | Study Design |
Country and participants | Observation period | Intervention description | Outcome (measures) | Results | Quality assessment rating |
Åkerstedt et al, 200124 | Longitudinal intervention study | Sweden, N=63, full-time workers in healthcare service. | 36 months | Intervention group (N=41): reduced WWH from 39 hrs/week to 30 hrs/week. Control group (N=22): unchanged working time. |
|
Subjective sleep quality (SSQ), mental fatigue and heart/respiratory symptoms, time for social activity, time for family and friends improved significantly more in the experimental group than in the control group. No significant effects for sickness absence or self-rated health. | Weak |
Wergeland et al, 200322 | Longitudinal intervention study | Norway and Sweden, N=403. Workers in nursing homes, home care services and kindergartens |
12–22 months | Intervention group: reduced DWH to 6 hrs/day. Reference group: unchanged working time. |
|
A significant interaction was found for neck-shoulder pain and for exhaustion after work in the intervention group. No significant effects were observed in the reference group. |
Weak |
von Thiele Schwarz et al, 200820 | Longitudinal intervention study | Sweden, N=177 employees from six workplaces at public dental healthcare organisation | 12 months | PE group: 2.5 hrs/week of physical activity instead of work time. Reduced work hours group: reduced WWH proportionally to the amount of time worked. Reference group: unchanged working time. |
|
Physical activity level increased in all three groups but significantly more in PE group. Glucose levels and upperextremity disorders were found to be significantly decreased in the exercise group, while a significant increase in HDL and waist-to-hip ratio was found among those working reduced hours. Participants working reduced hours also had significantly increased total cholesterol, while no changes in LDL-to-HDL ratio were recorded. |
Strong |
von Thiele Schwarz et al, 201121 | Longitudinal intervention study | Sweden, N=177 employees from six workplaces at a public dental healthcare organisation | 12 months | PE group: 2.5 hrs/week of physical activity instead of work time. Reduced work hours group: reduced WWH proportionally to the amount of time worked. Reference group: unchanged working time. |
|
Physical activity was significantly associated with an increase in self-rated productivity in terms of increased quantity of work and work-ability and decreased frequency and number of days of sickness absence. No effect was found in the work hours reduction group. In all three groups there was an increase in the number of treated patients per therapist, significantly greater in the reduced work hours group. | Strong |
Barck-Holst et al, 201718 | Longitudinal quasi-experimental trial | Sweden, N=204 A total of 125 participants were deemed as per protocol |
18 months | Intervention group: reduced work hours by 25%. Reference group: unchanged working time. |
|
The intervention group significantly improved restorative sleep, stress, memory difficulties, negative emotion, sleepiness, fatigue and exhaustion on both work days and weekends. Improved demands, instrumental manager support and work intrusion on private life were observed to be significantly higher in the intervention group. | Moderate |
Lorentzon 201723 | Longitudinal intervention study | Sweden, N=124, nurses working in a centre for the elderly | 23 months | Intervention group: work-time reduction to 6 hours/day. Reference group: unchanged working time. |
|
Good perceived health and alertness level, satisfactory level of perceived fatigue. Energy left at home, feeling calm, satisfactory levels of stress, average sleep time increased in intervention group. General symptoms, sleep and musculoskeletal symptoms improved in the intervention group, and dropped in the control group. Collaboration and personal development improved; improved sense of collaboration between nurses. Sick leave increased in the intervention group. No inferential statistics provided. |
Weak |
Schiller et al, 201719 | Longitudinal controlled intervention study | Sweden, N=580, workers from 33 workplaces in the public sector | 18 months | Intervention group: reduced WWH by 25%. Reference group: unchanged working time. |
|
On workdays, the intervention group displayed significantly improved SSQ, decreased sleepiness and perceived stress, less feelings of worries and stress at bedtime when work hours were reduced. Also, a significant 23 min extension of sleep duration was detected. The intervention showed similar positive effects on days off, except for sleep duration. |
Strong |
HDL, high-density lipoprotein; LDL, low-density lipoprotein; PE, physical exercise; WWH, weekly worked hours.