Bright light treatment used for adaptation to night work and re-adaptationback to day life. A field study at an oil platform in the North Sea

Night workers complain of sleepiness. reduced performance and disturbed sle ep due to lack of adjustment of the circadian rhythm. In simulated night-wo rk experiments scheduled exposure to bright light has been shown to reduce these complaints. Here we studied the effects of bright light treatment on the adaptation to 14 days of consecutive night work at an oil platform in t he North Sea, and the subsequent readaptation to day life at home, using th e Karolinska sleep/wake diary. Bright light treatment of 30 min per exposur e was applied during the first 4 nights of the night-shift period and the f irst 4 days at home following the shift period. The bright light exposure w as scheduled individually to phase delay the circadian rhythm. Bright light treatment modestly facilitated the subjective adaptation to night work, bu t the positive effect of bright light was especially pronounced during the re-adaptation back to day life following the return home. Sleepiness was re duced and the quality of day was rated better after exposure to bright ligh t. The modest effect of bright light at the platform was, possibly, related to the finding that the workers seemed to adapt to night work within a few days even without bright light. These results suggest that short-term brig ht light treatment may help the adaptation to an extended night-work period , and especially the subsequent re-adaptation to day life.