Original article

Scand J Work Environ Health 2003;29(1):22-26    pdf


Timed bright-light exposure and complaints related to shift work among women

by Leppämäki S, Partonen T, Piiroinen P, Haukka J, Lönnqvist J

Objectives This field study measured whether repeated, brief exposures to bright light during night shifts improved subjective well-being during and after night work. A secondary objective was to investigate whether this response differed by season (summer or winter), seasonality, or age.

Methods Eighty-seven healthy female nurses were voluntarily exposed to brief periods (4 x 20 minutes) of bright (5000 lux) light at scheduled times during every night shift over a 2-week period. Each morning following a night shift the subjects filled out self-assessment questionnaires measuring subjective symptoms and distress caused by work at night. The questionnaires were also completed 2 weeks before and after the light intervention. The study had two phases, summer (May-June) and winter (November-December). Thirty-seven of the subjects participated during both periods.

Results Light significantly alleviated the subjective distress associated with nightshift work, both in summer and in winter, independent of the subject`s age. The effect was stronger for those who reported routine seasonal changes in mood.

Conclusions Short pulses of timed bright-light exposure may enhance subjective adaptation to night work.

This article refers to the following texts of the Journal: 1998;24 suppl 3:115-120  1999;25(6):610-615  1996;22(2):133-138