SHIFTPLAN: an RCT Investigating the Effect of a Shift Work Intervention on Fatigue, Sleep and Health.

A Randomized Controlled Trial Investigating the Effects of a Multimodal Shift-work Intervention on Drivers' Fatigue, Sleep, Health and Performance Parameters.

Shift work is associated with disturbed life rhythms resulting from chronic exposure to circadian misalignment and sleep restriction, with long-term participation in most shift schedules causing serious health problems. Epidemiological data show that shift workers are at increased risk of sleepiness, fatigue and insomnia, cardiovascular disease, breast cancer and shift-work disorder. Prevalence estimates of shift-work disorder vary between 5% and 26,5%.

Given these widespread and serious health and functional consequences of shift work, there is a necessity for treatments that improve shift workers' health and work performance. Most non-pharmacological recommendations mention improved scheduling, bright-light exposure, napping, psychoeducation fostering sleep hygiene, and cognitive-behavioral interventions.

The effects of shift work on the health, fatigue and sleepiness of drivers have been robustly investigated in observational studies, as well as the effects of single measures such as scheduling or resting times. But studies on the effectiveness of countermeasures against the adverse impact of shift work are sparse, especially for high-risk populations such as professional drivers and controlled intervention studies are lacking. Several other investigators expounded the need for a multi-level approach to managing occupational sleep-related fatigue and workplace interventions to promote sleep and health of shift workers. Highlighting the high public-health burden associated with lack of recuperative sleep, the authors pointed out the pressing need to develop policies and implement programs aimed at improving workers' sleep health.

With SHIFTPLAN, the investigators aim to fill this gap in comprehensive approaches. To their knowledge, this is the first randomised controlled trial to systematically gauge the effect of a multimodal program that includes ergonomic shift scheduling and an educational program on well-defined health, sleep and performance outcomes in professional drivers.

The duration of the intervention will be six months. The intervention provided to the intervention group is based on evidence-based good standard of care and includes: 1) Healthy scheduling (fast forward-rotating shift schedules adapted to chronotype, adequate resting times, napping, bright-light therapy); 2) Education program for drivers (psychoeducation promoting sleep hygiene, cognitive-behavioral strategies, stress-management techniques, information on chronotherapy such as bright-light therapy and napping) The control group or "waiting-list group" will include drivers who will continue working according to the default shift schedules while being assigned to a waiting list in anticipation of the education program to which they will able to suscribe after completing the study.

Inclusion Criteria:

• - Professional drivers having worked in shifts with the transport company in full-time or ≥80% part-time employment in the company's regular backward-rotating schedule for at least two years.

Exclusion Criteria:

• Regular medication for high blood pressure and uncontrolled high blood pressure (defined as exceeding 140/90 mmHg) at screening, regular medication for diabetes, sleeping pills or sedative medication for depression (defined as trazodone, mirtazapine and amitriptyline). Because our secondary outcomes imply the evolution of blood-pressure and blood-sugar parameters, drivers with such pre-existing controlled or non-controlled comorbidity will not be eligible for participation.
• High risk of moderate-to-severe obstructive sleep apnea syndrome (OSAS) as assessed with the STOP-Bang questionnaire, a simple, easy to remember and self-reportable screening tool. We will use a cut-off score of 6 or higher to indicate the presence of OSAS.
• Drivers combining their job as a professional driver with another job elsewhere.
• Excessive sleepiness as defined as a score in excess of 12 on the Epworth Sleepiness Scale (ESS). Although the habitual cut-off is >9, we opted for this higher threshold because we will be examining the effect of the intervention on daytime sleepiness. All applicants with an ESS >12 will be excluded and referred to a general practitioner for further evaluation.
• A BMI higher than 35. We chose this cut-off value based on the data provided by the external occupational health service, which showed that in 2018, 42.6 % of their drivers had a mean BMI of 25-30 and 27.5 % a BMI between 30-40.
• The presence of major depression as defined by a score exceeding the threshold of 1.75 on the Hopkins Symptom Checklist (HSCL-25), where higher scores were demonstrated to be highly indicative of depressive disorder according to the DSM-5 and characterized as "a case requiring treatment".