BACKGROUND: The relative shortage of light during the decreasing photoperiod may compromise well-being. Earlier studies suggest that bright-light exposure may be of help to alleviate winter-bound symptoms. METHODS: We carried out a field study with exposure to bright light on office employees during winter. RESULTS: Repeated bright-light exposure improved vitality and reduced depressive symptoms. The benefit was observed not only in healthy subjects with season-dependent symptoms but also in those not having the seasonal variation. CONCLUSIONS: Bright-light exposure during winter appears to be effective at improving the health-related quality of life and alleviating distress in healthy subjects. CLINICAL IMPLICATIONS: Administration of bright light is a useful option to improve vitality and mood among subjects working indoors in wintertime. LIMITATIONS OF STUDY: Our field setting used self-reports, not interviews, for the assessment of outcome.