Bright light improves vitality and alleviates distress in healthy peopleTimo Partonen and Jouko Lönnqvist 1997-1998
Department of Mental Health and Alcohol Research, National Public Health Institute, Helsinki, Finland
Background. Season-bound changes in mood and behaviour may compromise well-being among healthy people. Earlier studies suggest that exposure to bright light would alleviate the winter-bound symptoms. The objectives of our study were to measure the intensity of symptoms suffered by office workers during winter, and to analyse the effects of exposure to bright light on health related quality of life and psychological distress.
Methods. We carried out a field study with exposure to bright light on office employees during winter. A total of 160 consecutive eligible subjects was enrolled. All the subjects were working while engaged in the study from November to February. We employed a crossover ABAB design in which two 4-week periods of using the light box (A) alternated with two 4-week periods of not using it (B). Subjects were instructed to use the lights, at work or home, for at least 1 hour a day on at least 5 days a week. At baseline the subjects were asked to fill in a Pre-intervention Expectations Questionnaire (PEQ) and the Seasonal Pattern Assessment Questionnaire (SPAQ). The Symptom Distress Checklist 90 (SCL-90), measuring psychological symptom profile or distress, and the RAND 36-item Health Survey 1,0 (RAND) were administered at baseline and immediately after each of the 4 periods of intervention. The former has a good power to discriminate between the scores of patient and community samples.1 The latter is sensitive to changes in health among general populations.2
Results. The repeated exposure to bright light reduced the intensity of symptoms of depression and hostility significantly and improved vitality significantly after both 4-week periods of the use of bright light, as rated at weeks 4 and 12. The response was not associated with the intensity of retrospectively scored season-dependent symptoms. The reduction of symptoms of depression and hostility and the improvement in vitality were not significantly explained by the pre-intervention expectations, arguing against a marked placebo effect in this study. Side-effects attributed to the use of bright light were reported by eight (12%) respondents, and they were given as the reason for drop out by two (3%).
Conclusions. Our key finding was that repeated systematic exposure to bright light reduced depression and hostility among healthy subjects. Second, our results also suggest that certain aspects of the health related quality of life, vitality in specific, may be improved.
Clinical implications. Administration of bright light is a useful option for improving vitality and alleviating psychological distress in healthy subjects working indoors in wintertime. Further studies are required to discover whether light administration in wintertime is a useful option for improving vitality and mood among people at large.
References.
- Holi, M., Sammallahti, P.R. and Aalberg, V.A. (1998) A Finnish validation study of the SCL-90. Acta Psychiatr. Scand. 97, 42-46.
- Hemingway, H., Stafford, M., Stansfeld, S., Shipley, M. and Marmot, M. (1997) Is the SF-36 a valid measure of change in population health? Results from the Whitehall II study. BMJ 315, 1273-1279.
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