Scand J Work Environ Health 2003;29(1):22-26 pdf
https://doi.org/10.5271/sjweh.700 | Issue date: Feb 2003
Timed bright-light exposure and complaints related to shift work among women
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.
Key terms bright-light exposure; circadian phase; phototherapy; seasonality; shift work; woman