Shift Workers' Health Behavior Action Program Across Europe

Inclusion Criteria: * Age ≥ 21 years * Work ≥ 24 hours per week * Shift work duration \> 3 years and currently doing night shifts * Expected to continue night shiftwork for at least 1 year after inclusion * On average working ≥ 4 night shifts per month * Working generally ≥ 2 consecutive night shifts * In possession of a smartphone and willing to download the study application Exclusion Criteria: * Body Mass Index (BMI) \< 18.5 or \> 40 kg/m2 * Pregnant or lactating * Chronic diseases with ongoing therapy (e.g. renal failure, active hepatitis, cirrhosis, myocardial infarction, chronic obstructive pulmonary disease and cancer) * Current or recent use of medications interfering with sleep, including: Central nervous system stimulants (e.g., Ritalin, Adderall, Modafinil or similar); Chronic use of sleep agents (e.g., benzodiazepine, non-hypnotic benzodiaze-pine, first-generation antihistamine, melatonin receptors agonists or similar); Other medications or combinations significantly affecting sleeping patterns * Recent or ongoing psychotherapy for sleep disorders * Current or recent use of medications affecting appetite or weight regulation, including: Appetite-enhancing/weight-gain medications (e.g., atypical antipsychotics, cor-ticosteroids such as prednisone, mirtazapine or similar); Appetite-suppressing/weight-loss medications (e.g., CNS stimulants such as Ritalin, Adderall, GLP-1 receptors agonists or similar); Other medications or combinations significantly influencing appetite or body weight * Participation in another human trial, lifestyle program or weight loss intervention within the past 3 months * Planned surgical procedure during the study period * History of or planned bariatric surgery/treatment