Figure 1.

Baseline melatonin profiles for rats prior to MCAo. Melatonin profiles were obtained for all animals prior to MCAo to determine baseline timing. Measurements were made for up to six days, and, in all cases, the daily melatonin timing was stable. Therefore, only a single day's tracing of each individual is shown in this composite illustration. Animals exhibit a wide range of timing profiles. There is a broader range of MT-on times compared to MT-off times. The melatonin duration is defined as the time between the MT-on and MT-off. The MT-on is defined as the time when melatonin rises to 20% of the daily maximum (set to 100%). The MT-off is defined as the time when the melatonin level falls to 20% of the daily maximum. The gray shaded area represents time of lights off.