Abstract:
Post–operative sleep disruption is common among patients who undergo general anaesthesia. The reason for this can be partly attributed to a disruption of the circadian clock. It has been shown that a 6–hour isoflurane anaesthetic administered to the honey bee (Apis mellifera) under constant conditions during the subjective day time causes a phase delay of the circadian clock, or „jetlag‟. This phase shift in turn results in altered time perception following anaesthesia. By contrast, a 6–hour isoflurane anaesthesia is administered during the subjective night time, does not elicit a phase shift. The aims of this thesis were to: 1) determine whether the phase shifting effect of anaesthesia persists in the presence of daily light/ dark cycles in order to ascertain whether the effect is relevant to the normal environment under which patient receive anaesthesia 2) determine whether the phase delay can be eliminated with the concurrent administration of bright light 3) to accurately describe the time dependency of the effect of isoflurane on the clock, and compare this to the effect of light and 4) determine whether the phase shifting effect of isoflurane is due to anaesthesia or to exposure to a volatile chemical. Results from these experiments indicate that day time anaesthesia administered in the presence of strong light/ dark cycles elicits an average phase delay of –1.24 hours on the first post–anaesthetic day (compared with –3.5 hours under constant conditions) and that this shift is effectively removed by concurrent exposure to light and anaesthesia.
