Night Work Hours Reduction Trial

NCT07848607 | Not Yet Recruiting

• 1 other identifier: WHRedu-36
• Study Type: interventional
• Target: 200
• Locations: 1 country
• Sites: 3

Brief Summary

The primary aim of this study is to investigate the effects of reducing weekly working hours among employees working night shifts regularly from 38 hours 15 minutes to 36 hours on payroll-based, objective working-hour characteristics, sickness absence, and workforce retention. The secondary aim is to investigate experiences of promoting and hindering factors related to the working-hour reduction, its implementation process, and perceived benefits and challenges. The working-hour reduction will be implemented in three Finnish wellbeing services counties with different starting dates, the first being in late September 2026 and the latest in early 2027. The working-hour reduction has been agreed upon by the parties to the collective agreement for Finnish public social and health care. Thus, intervention is a so-called natural experiment in a real-life setting. The effects of the intervention will be evaluated using a quasi-experimental design with staggered, non-randomized implementation across participating counties. Administrative, payroll-based, employer-owned working-hour data, including records of sickness absences without any medical or health information and other absences (including unpaid, education, and childcare), will be used to compare changes before and during the intervention among work units participating in the working-hour reduction. The investigation will also utilize matched work units that do not participate in the reduction (i.e., intervention) as control units (i.e., continuing standard working-hour arrangements).

Conditions

Night Shift Work; Sickness Absence

Keywords

Working Time Reduction; Reduced Working Hours; Night Work; Night Shift Work; Healthcare Workers; Sickness Absence; Employee turnover; Payroll-Based Working Hour Data; Quasi-experimental Study

Outcome Measures

Primary Outcomes (5)

• Sickness Absence Rate

  Percentage of working time lost due to sickness absence, derived from administrative, payroll-based employer records. No medical or diagnostic information will be collected.

  From enrollment to the end of treatment at 66 weeks.

• Employee Turnover

  Termination of employment during the follow-up period, derived from employment records.

  From enrollment to the end of treatment at 66 weeks.

• Retention of Employees Performing Night Work

  Proportion of employees performing regular night work who remain employed and performing night shifts during the follow-up period.

  From enrollment to the end of treatment at 66 weeks.

• Total Weekly Working Hours

  Average number of paid working hours per week, derived from administrative, payroll-based working-hour records.

  From enrollment to the end of treatment at 66 weeks.

• Number of Morning, Day, Evening, and Night Shifts

  Number or rate of shifts worked during each scheduling period, categorized according to shift type (morning, day, evening, and night) using employer payroll-based working-hour records.

  From enrollment to the end of treatment at 66 weeks.

Secondary Outcomes (13)

• Number of Sickness Absence Episodes

  From enrollment to the end of treatment at 66 weeks.

• Total Sickness Absence Days from Short Episodes (1-5 days) of Sickness Absence

  From enrollment to the end of treatment at 66 weeks.

• Short-Term Sickness Absence Episodes (1-5 Days)

  From enrollment to the end of treatment at 66 weeks.

• Number of Consecutive Shifts

  From enrollment to the end of treatment at 66 weeks.

• Overtime Hours

  From enrollment to the end of treatment at 66 weeks.

Study Arms (2)

Reduced working hours (36 h)

EXPERIMENTAL

Reduced working hours (36 h) for those who regularly conduct night shift work.

Other: Reduced Working Hours (from 38h15minutes to 36h)

Standard working hours (38 h 15 min)

NO INTERVENTION

Standard working hours (38 h 15 min) for those whose organisation or unit did not choose to participate in the trial.

Interventions

Reduced Working Hours (from 38h15minutes to 36h) OTHER

Reduced Working Hours (from 38h15minutes to 36h) for those conducting night shift work regularly

Reduced working hours (36 h)

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Employment in one of the participating Finnish wellbeing services counties. Employees working in work units participating in the study. For the primary analyses, employees who work regular night shifts. Employees with available administrative, payroll-based working-hour and employment records.

You may not qualify if:

• Exclusive day workers. Employees performing shift work that does not include night shifts. For the primary analyses, employees not engaged in regular night work.
• Employees not performing regular night work may be included in secondary analyses evaluating workplace-level spillover effects.

Sponsors & Collaborators

• Finnish Institute of Occupational Health: lead
• Finnish Work Environment Fund: collaborator

Study Sites (3)

Kainuun hyvinvointialue

Kajaani, Finland

Location

Päijät-Hämeen hyvinvointialue

Lahti, Finland

Location

Pohjois-Pohjanmaan hyvinvointialue

Oulu, Finland

Location

Related Publications (11)

• Voglino G, Savatteri A, Gualano MR, Catozzi D, Rousset S, Boietti E, Bert F, Siliquini R. How the reduction of working hours could influence health outcomes: a systematic review of published studies. BMJ Open. 2022 Apr 1;12(4):e051131. doi: 10.1136/bmjopen-2021-051131.

  PMID: 35365508 BACKGROUND

• Turunen J, Karhula K, Ropponen A, Shiri R, Hamalainen K, Ervasti J, Koskinen A, Haavisto O, Sallinen M, Pehkonen J, Harma M. Evaluating quick return restrictions on sickness absence in healthcare employees: A difference-in-differences study. Int J Nurs Stud. 2025 Mar;163:104996. doi: 10.1016/j.ijnurstu.2025.104996. Epub 2025 Jan 10.

  PMID: 39836993 BACKGROUND

• Turunen J, Karhula K, Ropponen A, Koskinen A, Hakola T, Puttonen S, Hamalainen K, Pehkonen J, Harma M. The effects of using participatory working time scheduling software on sickness absence: A difference-in-differences study. Int J Nurs Stud. 2020 Dec;112:103716. doi: 10.1016/j.ijnurstu.2020.103716. Epub 2020 Jul 14.

  PMID: 32736788 BACKGROUND

• Ropponen A, Hirvonen M, Kuusi T, Harma M. Concurrent Trajectories of Objectively Measured Insufficient Recovery and Workload Among a Cohort of Shift Working Hospital Employees: Quantitative Empirical Research. Nurs Open. 2024 Nov;11(11):e70101. doi: 10.1002/nop2.70101.

  PMID: 39571045 BACKGROUND

• Neubert, S., Bader, C., Hanbury, H., & Moser, S. (2022). Free days for future? Longitudinal effects of working time reductions on individual well-being and environmental behaviour. Journal of Environmental Psychology, 82, 101849. https://doi.org/https://doi.org/10.1016/j.jenvp.2022.101849

  BACKGROUND

• Krutova O, Koskinen A, Peutere L, Ervasti J, Virtanen M, Harma M, Ropponen A. A Longitudinal Study on Trajectories of Night Work and Sickness Absence among Hospital Employees. Int J Environ Res Public Health. 2022 Jul 3;19(13):8168. doi: 10.3390/ijerph19138168.

  PMID: 35805827 BACKGROUND

• Kecklund G, Axelsson J. Health consequences of shift work and insufficient sleep. BMJ. 2016 Nov 1;355:i5210. doi: 10.1136/bmj.i5210.

  PMID: 27803010 BACKGROUND

• IARC Working Group on the Identification of Carcinogenic Hazards to Humans. Night Shift Work. Lyon (FR): International Agency for Research on Cancer; 2020. Available from http://www.ncbi.nlm.nih.gov/books/NBK568195/

  PMID: 33656825 BACKGROUND

• Harma M, Karhula K, Turunen J, Koskinen A, Shiri R, Sallinen M, Vanttola P, Haavisto O, Hakola T, Ropponen A. Working time traffic light recommendations: development, use, and implementation in the Finnish social and healthcare. Ind Health. 2026 May 20;64(3):214-232. doi: 10.2486/indhealth.2025-0082. Epub 2025 Sep 15.

  PMID: 40958582 BACKGROUND

• Harma M, Ropponen A, Hakola T, Koskinen A, Vanttola P, Puttonen S, Sallinen M, Salo P, Oksanen T, Pentti J, Vahtera J, Kivimaki M. Developing register-based measures for assessment of working time patterns for epidemiologic studies. Scand J Work Environ Health. 2015 May 1;41(3):268-79. doi: 10.5271/sjweh.3492. Epub 2015 Mar 19.

  PMID: 25788103 BACKGROUND

• Hanbury, H., Illien, P., Ming, E., Moser, S., Bader, C., & Neubert, S. (2023). Working less for more? A systematic review of the social, economic, and ecological effects of working time reduction policies in the global North. Sustainability: Science, Practice and Policy, 19(1), 2222595. https://doi.org/10.1080/15487733.2023.2222595

  BACKGROUND

Central Study Contacts

Annina Ropponen, Professor

CONTACT

+358304742012; annina.ropponen@ttl.fi

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Participants are effectively in one of two concurrent conditions: 1. Reduced working hours (36 h) 2. Standard working hours (38 h 15 min)

Study Record Dates

• First Submitted: September 17, 2026
• First Posted: September 30, 2026
• Study Start: September 30, 2026
• Primary Completion (Estimated): February 28, 2028
• Study Completion (Estimated): April 1, 2028
• Last Updated: September 30, 2026

Record last verified: 2026-09

Data Sharing

• IPD Sharing: Will not share

Locations

FI (3)