Summary of findings for the main comparison. Summary of findings: primary health outcomes ‐ temporal flexibility.
| Study | Intervention | Population and setting | Follow‐up period & final sample size | Primary outcomes | Summary findings |
| De Raeve 2007 | Overtime | Various settings (45 companies), the Netherlands Blue and white collar workers, mostly male (82.5% male in population from which sample was taken) |
12 and 24‐month follow up Final sample n = 1871; 252 intervention, 1619 control |
Mental health: psychological stress, GHQ‐12 (Goldberg 1991) General health: self‐rated general health (one item from the SF‐36 Aaronson 1998); prolonged fatigue (20 items, Checklist Individual Strength Vercoulen 1994) and need for recovery from work (11 items, VBBA, van Veldhoven 2003) |
There were no statistically significant associations between overtime and need for recovery or psychological distress in either men or women. Reference = no overtime at T1 or T2 Transition from no overtime at T1 to overtime at T2 Adjusted OR 95% CI Men Need for recovery 1.31 (0.87 to 1.98) Psychological distress 1.16 (0.83 to 1.64) Women Need for recovery 1.47 (0.64 to 3.38) Psychological distress 0.81 (0.40 to 1.62) Transition from overtime at T1 and no overtime at T2 Men Need for recovery 1.63 (1.23 to 2.15) Psychological distress 0.82 (0.64 to 1.05) Women Need for recovery 1.96 (1.04 to 3.69) Psychological distress 1.00 (0.63 to 1.59) Overtime at both T1 and T2 Men Need for recovery 0.58 (0.36 to 0.93) Psychological distress 0.69 (0.49 to 0.98) Women Need for recovery 0.44 (0.15 to 1.27) Psychological distress 0.69 (0.37 to 1.29) |
| Dunham 1987 | Flextime, with a core working period between 1.30 and 3.30, but with flexibility regarding start and finish times and timing and duration of lunch breaks. Workers were required to plan their schedules one week in advance and supervisors could request changes to facilitate department functioning. | Corporate office of a Midwestern utility organisation, USA. Non‐supervisory (professional, clerical, and technical) and supervisory personnel. Data on male:female ratio not reported. | 3 and 6 months follow up Final sample size n = 102; 55 intervention, 47 control |
Physiological and psychological stress, 7‐item scale (Patchen 1970) |
No significant change in psychological stress or psychological stress Dunn Bonferroni statistics Physiological stress: Pretest and first post‐test: ‐0.487 Pretest and second post‐test: ‐0.708 Second and first post‐test: ‐0.262 Psychological stress: Pretest and first post‐test: ‐0.757 Pretest and second post‐test: ‐0.778 Second and first post‐test: ‐0.099 |
| Kandolin 1996 | Self‐scheduling of hours (part of a multiple intervention with changes to shift rotation including slow to fast rotation and backward to forward rotation) | Hospital, Finland Midwives, all female |
6‐month follow up Final sample n = 58; 45 intervention, 13 control |
Mental stress, tiredness, mental strain (Standard Shiftwork Index, Barton 1992 and Occupational Stress Questionnaire, Elo 1992) | A significant decrease in tiredness (defined as rather or very tired) during night shift (from 53% to 44%) was noted, time x group interaction P = 0.02 Non‐significant differences in mental stress (somewhat or much mental stress) and mental strain (rather or very strenuous) Mental strain (morning shift) Intervention, Before 27% Intervention, After 11% Time*group P = 0.09 Mental strain (evening shift) Intervention, Before 17% Intervention, After 9% Time*group P = 0.29 Mental stress Intervention, Before 27% Intervention, After 15% Time*group P = 0.07 |
| Pryce 2006 | Open‐rota scheduling system. Within this system employees were asked to schedule their shift preferences into an open (uncompleted) rota. The rota was then fine‐tuned by one or two staff members and this responsibility was rotated each week between the staff. | Psychiatric hospital, Denmark 60% nurses, 40% healthcare workers, predominantly female (92%) |
20‐month follow up Final sample n = 166; 80 intervention, 86 control |
Mental health: Stress symptoms, three 4‐item scales: behavioural cognitive and somatic symptoms (Setterlind 1995) Vitality, 4 items (Setterlind 1995) General health: Global self‐rated health (Borg 2000) |
No significant benefits to any of the health outcomes were reported but non‐significant trends were noted for somatic symptoms and vitality Mean (SD), F‐ratio (df) Self‐rated health Int Pre 58.48 (16.56) Int Post 60.07 (23.04) Con Pre 60.33 (20.12) Con Post 58.82 (29.01) F (176) = 0.34 Behavioural symptoms Int Pre 21.93 (18.01) Int Post 20.01 (16.43) Con Pre 20.01 (15.64) Con Post 23.34 (15.66) F (174) = 0.95 Cognitive symptoms Int Pre 27.04 (15.03) Int Post 29.54 (20.03) Con Pre 26.48 (16.63) Con Post 30.06 (16.88) F (174) = 0.99 Somatic symptoms Int Pre 33.53 (13.33) Int Post 34.33 (13.65) Con Pre 34.75 (10.81) Con Post 38.45 (10.75) F (175) = 1.25 Vitality Int Pre 54.47 (15.90) Int Post 56.67 Con Pre 63.50 (16.23) Con Post 57.36 (17.36) F (174) = 1.72 |
| Smith 1998 | CWW, 5 or 7 8‐hour shifts with 2 or 3 days off to either (a) flexible starts with 4 12‐hour shifts, then 4 days off or (b) rigid starts with 4 12‐hour shifts, then 4 days off | Police service, UK Police officers, mostly male |
6‐month follow up, final sample n = 45, 27 intervention 18 control (numbers of participants on flexible and fixed starts unclear, presumably approx 50% in each) | Physical health questionnaire (Barton 1995); sleep alertness, chronic fatigue (Standard Shiftwork Index); psychological stress (GHQ‐12, Goldberg 1972) | No significant changes for physical health measures (including digestive problems, cardiovascular problems and pain ‐ data not reported). A significant interaction effect on psychological wellbeing was found (F = 5.11, P < 0.05) with mental health improving on the flexible system but worsening on the rigid rota. Interaction effects were also observed for day shift sleep quality (F = 4.59, P < 0.05), night shift alertness (F = 4.21, P < 0.05), night shift sleep durations (F = 6.49, P < 0.05). No significant interaction effect was observed for day shift alertness (F = 1.75, P > 0.05) or night shift sleep quality (data not given) |
| Viitasalo 2008 | Flexibility of a shift system The intervention involved some individual control and choice regarding shift preferences which was balanced against employer needs. Rosters were issued 4 weeks in advance, after which the employer could only make changes in the rotas of the 3rd or 4th week in case of changed operational needs. |
Airline company (line maintenance), Finland Maintenance workers, all male |
7 to 8 months follow up Final sample n = 84; 22 intervention, 22 control (no change backward rotating) 40 control (change to rapidly forward rotating) |
Physical health experimental measures: blood pressure, heart rate, total cholesterol, HDL, LDL, triglycerides, fasting plasma glucose, glycosylated haemoglobin, C‐ reactive protein General health: Sleepiness and sleep disturbances; falling asleep at work (Epworth Sleepiness Scale, ESS, Johns 1991) |
Mean systolic BP decreased from 142 to 136 mm Hg (P = 0.049) and heart rate decreased from 66 to 60 beats/minute (P = 0.06) in the experimental group when compared to the other groups ( rapid forward rotation BP increased by 2.5 mmHg, control group no change in BP) Changes in diastolic BP were not significant (exact figures not given, graphs only) Changes in the ESS scale (probability of falling asleep at work) decreased but the change was not statistically significant (intervention group score decreased from 7.5 (SD 5.3) to 7.1 (SD 4.4) and control group (no change) increased from 7.8 (SD 3.8) to 8.3 (SD 3.9). For the group changing to forward rotating the ESS score showed a slight decrease from 6.4 (SD 2.7) to 6.2 (SD 3.5). Daytime sleepiness showed a declining trend in all 3 groups (P = 0.06). No statistically significant differences in the interaction between time and group were observed for the following biomarkers: Total cholesterol (mmol/l) Mean (SD) Int Pre 5.0 (0.7) Int Post 5.0 (0.8) Con Pre 5.2 (1.1) Con Post 5.3 (1.2) HDL cholesterol (mmol/l) Mean (SD) Int Pre 1.3 (0.3) Int Post 1.4 (0.3) Con Pre1.5 (0.3) Con Post 1.6 (0.3) LDL cholesterol (mmol/l) Mean (SD) Int Pre 3.2 (0.7) Int Post 3.1 (0.8) Con Pre 3.0 (0.9) Con Post 3.1 (1.0) Triglycerides (mmol/l) Mean (SD) Int Pre 1.3 (0.6) Int Post 1.3 (0.7) Con Pre 1.2 (0.9) Con Post 1.3 (0.7) Fasting plasma glucose (mmol/l) Mean (SD) Int Pre 5.2 (0.4) Int Post 5.0 (0.4) Con Pre 5.2 (0.4) Con Post 5.0 (0.5) Glycosylated haemoglobin (%) Mean (SD) Int Pre 5.1 (0.3) Int Post 4.9 (0.4) Con Pre 5.1 (0.2) Con Post 5.0 (0.4) High sensitivity C reactive protein (mg/l ) Mean (SD) Int Pre 0.8 (0.8) Int Post 1.1 (1.2) Con Pre 0.9 (0.6) Con Post 1.2 (1.0) |
BP = blood pressure; Con = control; CWW = compressed working week; ESS = Epworth Sleepiness Scale; GHQ = General Health Questionnaire; HDL = high‐density lipoprotein; Int = intervention; LDL = low‐density lipoprotein; SD = standard deviation