Impact of light exposure for adapting to day and shiftwork, above and below ground, as well as during different seasons

Project leader

Funding source

Forte - Swedish Research Council for Health, Working Life and Welfare

Project Details

Start date: 01/01/2012
End date: 31/12/2014
Funding: 2700000 SEK


The brain knows time of day through light exposure, a crucial help for organizing body restitution. Light exposure is also an important factor for adaptation to odd work hours. Those who work irregularly show rhythm problems or circadian stress that causes fatigue, mood deterioration, sleep problems, reduced work performance and ill health. This study examines what levels of light intake is needed to avoid problems. We see a unique opportunity to examine the scarcity of light at LKAB in Kiruna, using miners working under and above ground, during dark and light seasons, and in working with and without shifts. The group is large (˜ 1600 workers) enough to study whether genetic differences in clock genes that control the daily rhythm is important for the adaptation of work hours, using questionnaires and DNA swabs. In the next step we can for the first time be able to obtain detailed knowledge about the intensity and frequency of light exposure on and off the job that will best help the adaptation to work hours.

Study 1 is carried out during the dark season, and covers all employees that answer a question battery and give saliva for DNA testing. The battery contains questions on sleep behaviour, sleep disorders, light behaviour and chronotype (morningness/eveningness). Based on responses, sub-groups will be invited to study 2,

In Study 2 workers will be followed over 4 weeks with a hand held actigraph, diaries (sleep/mood) and light meter (lux/irradiance - red, green , blue). The actigraph consists of a wrist-mounted clock that detects movement in every minute and provides a definition of sleep/wakefulness rhythms and sleep quality. Three groups, 30 shift workers below ground, 30 shift workers above ground, and 30 daytime workers are studied across two years both during spring and winter, when light exposure differ. The study aims to describe how much light is needed to be able to handle shiftwork and give advice of how to cope with light scarcity.

Last updated on 2017-29-03 at 17:13