Abstract
In most studies, the magnitude and rate of adaptation to various night work schedule is assessed using core body temperature as the marker of circadian phase. The ai: of the current study was to assess adaptation to a simulated night work schedule usir salivary dim light melatonin onset (DLMO) as an alternative circadian phase marke It was hypothesised that the night work schedule would result in a phase dela manifest in relatively later DLMO, but that this delay would be somewhat inhibit by exposure to natural light. Participants worked seven consecutive simulatf 8-hour night shifts (23:00-07:OOh). By night 7, there was a mean cumulative pha; delay of 5.5 hours, equivalent to an average delay of 0.8 hours per day. Th indicates that partial circadian adaptation occurred in response to the simulated nigJ work schedule. The radioimmunoassay used in the current study provides sensitive assessment of melatonin concentration in saliva that can be used 1 determine DLMO, and thus provides an alternative phase marker to core bod temperature, at least in laboratory studies.
