The investigators will conduct a cross sectional study in 5 European countries (Austria, Denmark, Germany, Netherlands and Poland) and recruit 1000 rotating night shift workers and day workers (200/country) from the health sector and different industries. Night and day workers will be age-frequency (3 age groups), gender and (where possible) working tasks matched. Participants will complete online questionnaires and report their diet habits in a mobile app. Body composition, dietary behavior and sensory preferences will be tested. Biologic specimens (blood, urine, saliva, hair and feces) will be collected at the workplace on a day where participants are working on a day shift (or a day off). In a subsample (Austria and Netherlands) shift workers will provide biological samples (spot blood, urine and saliva) both on a day shift and on a night shift. Biomarkers including hormones, cellular immunity and inflammation, parameters linked to gut health and metabolism of fat and sugar, appetite, oxidative stress, metabolomics and microbiota will be measured. The investigators hypothesize that compared to day workers, night shift workers will experience disrupted levels of pre-obesity markers. Higher circadian disruption, sleep disruption and mistimed eating patterns workers will be associated with more disrupted biomarker profiles. Among rotating shift workers, night shift will be associated with acute disrupted melatonin production, metabolomic profiles and composition of oral microbiota compared to a day shift. conditions: Obesity conditions: Shift-work Disorder conditions: Circadian Rhythm Disorders studyType: OBSERVATIONAL observationalModel: CASE_CONTROL timePerspective: CROSS_SECTIONAL count: 1000 type: ESTIMATED name: No intervention measure: high-sensitive C-Reactive Protein (hs-CRP) measure: The investigators will consider levels of hormones in plasma measure: The investigators will consider levels of hormones in plasma measure: The investigators will consider levels of parameters linked to gut health in serum and in feces measure: The investigators will consider levels of parameters linked to gut health in serum and in feces measure: The investigators will consider levels of parameters linked to gut health in serum and in feces measure: The investigators will consider levels of parameters linked to gut health in serum and in feces measure: The investigators will consider parameters of cellular immunity and inflammation in plasma measure: The investigators will consider parameters of cellular immunity and inflammation in plasma measure: The investigators will consider parameters of cellular immunity and inflammation in plasma measure: The investigators will consider parameters of metabolism of fat and sugar in plasma measure: The investigators will consider parameters of metabolism of fat and sugar in plasma measure: The investigators will consider parameters of metabolism of fat and sugar in plasma measure: The investigators will consider parameters of metabolism of fat and sugar in plasma measure: The investigators will consider parameters of metabolism of fat and sugar in plasma measure: The investigators will consider levels of appetite markers in plasma measure: The investigators will consider levels of appetite markers in plasma measure: The investigators will consider levels of oxidative stress in whole blood, serum, plasma and urine measure: The investigators will consider levels of oxidative stress in whole blood, serum, plasma and urine measure: The investigators will consider levels of oxidative stress in whole blood, serum, plasma and urine measure: The investigators will consider levels of oxidative stress in whole blood, serum, plasma and urine measure: The investigators will consider levels of oxidative stress in whole blood, serum, plasma and urine measure: The investigators will consider metabolomics analysis of plasma samples and dry blood spots (DBS) measure: The investigators will consider microbiome analysis of feces samples and tongue swabs sex: ALL minimumAge: 21 Years stdAges: ADULT stdAges: OLDER_ADULT hasResults: False