Dear Shoishoi,

Thank you for your interesting comment. The cohort in our study, civil servants, is likely to work indoors and thus is little exposed to daylight during their workday. Exposure to daylight is also likely to be lower in that group compared to those working normal hours. However, civil servants in this study were all daytime workers working office hours and our reference group worked 7-8 hours, most of these during the peak sunlight hours in England. So those working 11 or more hours are unlikely to have missed plenty of light compared to the reference group. However, this would be an interesting point to be examined where data are available. We had quite a simple question of "hours worked on an average working day" and we had no questions about seasonal changes in mood. However, another study suggests that working evening and night shifts but not daytime work is associated with seasonal changes in mood and behavior, particularly in men (Pajunen et al., Scand J Work Environ Health 2007). This leads to a question of what effects long hours would have especially on shift workers.
Best wishes,
Marianna Virtanen