The impact of reduced worktime on sleep and perceived stress - a group randomized intervention study using diary data

What the research tells us

With retained salary and funding for additional staff, reduced worktime was associated at 18 months with approximately 23 more minutes of diary-reported sleep on workdays and less perceived stress and sleepiness. The effect concerns this combined arrangement, not every possible four-day-week policy.

Scope & interpretation

One workplace was assigned nonrandomly to control because of recruitment conditions. Post-allocation adherence/follow-up criteria mean this is not a complete intention-to-treat analysis. Self-reported diaries, clustering and selective retention constrain interpretation.

Study at a glance

POPULATION & SAMPLE

33 workplaces and 580 analysed participants: 354 intervention and 226 control, 76% women. Of 919 initially included, 98 withdrew after allocation and further analysis criteria were applied.

EXPOSURE / INTERVENTION / SUBJECT

Planned 25% worktime reduction with salary retained, extra hiring funds and restrictions on additional paid work; usual arrangements in controls. Actual reduction was about 20% in diary weeks and 25% in monthly payroll records.

OUTCOMES

Diary sleep, sleepiness and perceived stress; no common objective physiological-recovery endpoint.

TIME FRAME

18-month intervention follow-up.