Night Work Hours Reduction Trial

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).