EuRhythDia is a multicenter, controlled and randomized study. The aim of the study is to investigate the effects of 12 weeks of randomized timed light therapy or timed physical exercise as a chronotherapeutic lifestyle intervention on markers of central and peripheral circadian rhythms and cardiometabolic function in healthy night shift workers.

Lifestyle interventions have been recognized as important means to prevent and treat cardiometabolic disease. However, compliance of the European population to general recommendations of exercise and weight loss is unsatisfactory. There have been no studies that have attempted to convert the exciting new experimental data on the circadian clock, lifestyle, and cardiometabolic risk into diagnostic tools or novel therapeutic approaches via structured multidisciplinary efforts. One of the aims of the EuRhytDia study is to study novel applications of established lifestyle interventions by co-ordinating the timing of interventions with circadian rhythmicity.

Inclusion Criteria:

• Male and female subjects above the age of 18
• Night shift workers on regular night shifts with at least 3 nights in a row per month during the study period
• Subjects must have been on night shifts for at least 4 weeks before inclusion into the study
• Signed written informed consent

Exclusion Criteria:

• Regular use of drugs (prescription or non-prescription, exception: contraceptives) or dietary supplements within 4 weeks before inclusion of the study
• Pregnancy or breast feeding
• Any severe somatic or psychic disease (malignant or non-malignant
• Any known ophthalmological condition that prevents the exposure to bright light (e.g. cataract, glaucoma, retinopathy, macular degeneration, acute eye infections, lesions of the cornea)
• Any skin condition or use of drugs associated with increased photosensitivity;
• Any kind of disability that would prevent the subjects from participation in exercise training sessions