Wake after sleep onset (min spent awake/main sleep episode), derived from actigraphy data

Diet quality score: Eetscore™, a 55-item FFQ which is scored with the Dutch Healthy Diet 2015-index to evaluate adherence to the Dutch food-based dietary guideline; resulting in a total score between zero (no adherence) and 100 (complete adherence).

Light, moderate, vigorous activity (min), Sedentary time (min) as measured with an actigraphy (Motionwatch)

Perceived stress score (PSS-10), a 10-item validated questionnaire assessing the extent to which individuals perceive their lives as unpredictable, uncontrollable, and overloaded. Items are rated on a 5-point Likert scale referring to experiences over the past month; higher score mean more stress.

Insomnia severity (0-28): a 7-item self-administered questionnaire validated in shift workers as a proxy for sleep quality. Items assess the severity of insomnia symptoms, including difficulties with sleep onset, maintenance, and early awakening. Each item is scored 0-4, with total scores ranging from 0 to 28; higher scores indicate more severe insomnia

Shift Work Disorder Questionnaire (SWDQ): a 4-item questionnaire assessing sleep patterns, excessive sleepiness, and functional impairment related to shift work (53). Each item is scored 1-4, yielding a total score of 4-16, with higher scores reflecting greater symptom severit

Meal timing, frequency, regularity; using the Chrono nutrition Questionnaire for Shift Workers (CNQ-Shift). The questionnaire contains 20-23 questions, five questions each for morning, afternoon, and night shifts, three split shifts questions (if applicable), and two questions for work-free days.

FFPQ (liking/wanting scores): Participants rate "how pleasant it would be to try a bite of this food," using a 100-point visual analogue scale (explicit liking). A forced choice procedure is then carried used to assess which food participants would "most like to eat now" (implicit wanting).

OSPAQ (min)

Work-related sense of coherence Work-Soc (5-point Likert scale), a 9-scale assessing individuals' perceived comprehensibility, manageability, and meaningfulness at work.

Satisfaction With Life Scale (SWLS): a 5-item questionnaire evaluating global life satisfaction (66). Items are rated on a 7-point scale

Action planning, Coping planning, Habit formation, Intention. All items are scored on a either a 5 or 7-point Likert scale ranging from totally disagree to totally agree.

Hair cortisol concentraition (HCC), pg/mg hair

fasted blood glucose (mM)

fasted plasma insulin (pmol/L)

fasted blood lipids (mmol/L)

Diastolic and systolic blood pressure in fasted state (mmHg)

urinary melatonin (ng/mL)

assessed using a study-specific questionnaire evaluating participants' experiences with the intervention content, delivery, usability, and perceived burden of the intervention