Fig. 2.

Difference in weight reduction between the 2nd and the 1st trial sessions depending on the time of year (downward bars indicate that the 2nd session was more efficacious than the 1st one). The difference was greater when the 2nd session occurred in spring than in winter (first two vs. last two bars combined, effect of season). However, the light session was consistently more efficacious towards weight loss than placebo session (open vs. dark bars combined, effect of intervention). Two subjects who performed the study over two different winters, were not included in the diagram; both were non-seasonals. The effect of seasons is obviously attributable to a change (∆) in photoperiod, not ambient light (as January and February happened to be very sunny during both years).