Experimental design. Arrows indicate the transfer of parasites to recipient hosts (eight groups of five mice) within and between two rooms with opposite light schedules. Parasites remaining in the same room are matched to host rhythms and act as controls. Parasites transferred between rooms to hosts that are on the opposite rhythm to the parasite donor were temporally mismatched, analogous to jetlag. At the time of transfer, parasites originating from the standard light regime donor were at ring stage and those originating from the reversed light regime donor were at trophozoite stage and infections were initiated via either intraperitoneal (IP) or intravenous (IV) routes. Dark and light bars indicate lights on/off status throughout a 48-hour period. Zeitgeber time (ZT) is displayed above the bars; ZT 0/24, the time of lights on and ZT 12, time of lights off.