Inclusion Criteria:  Men and women Age 20-50 years Working ≥ 80% full-time equivalent over the previous month and during the study Working night shifts (i.e. shifts that comprise working hours between 23h and 06h) in rotation with day shifts (i.e. shifts that comprise working hours between 06h and 20h) Planned to work at least 3 consecutive night shifts during the study preceded by at least a day off or day shift Planned to work at least 3 consecutive day shifts during the study Confident use of a smartphone compatible with the study application (iOS, Android) and able to regularly take pictures of consumed food/drinks Able to give a fully informed consent and follow the study procedures  Exclusion Criteria:  Planned or current pregnancy during the study Menopausal women Major illness or hospitalization over the previous month Carries a pacemaker, pump or other medical device that can be disabled by a magnet Major mental illness Trip to a different time zone (≥ 2-hour time difference) over the previous month or planned during the study Enrolled in an interventional clinical trial (potentially interfering with the main outcomes) over the previous month or planned during the study