Certain shift schedules result in light exposure profiles that may cause circadian disruption. Previous studies estimated average artificial illuminance to quantify light at night (LAN) at work which limits their validity and scope. However, daylight, shift length, commuting exposures and light during restricted sleep opportunities compete with LAN as causative agents, as do non-photic factors such as social disruption, activity and food intake during the subjective night.

Investigations into the effects of light in shift work should be supported by 24-hour light exposure measurements, e.g. to establish dose-response relationships. The purpose of the study was to collect and suggest interpretations of 24-hour exposure data, and investigate both daytime and night-time workers' light cycles in more detail.

The complete article is a chapter of the book "Proceedings of the 29th CIE SESSION Washington D.C., USA, June 14-22, 2019" (http://files.cie.co.at/x046_2019/x046-PP30.pdf).