Been looking on the US RW forums and found this explanation:
Blood flow changes to keep you warmer (more to the surface if you are a little cold, switching to mostly to the core if you get REALLY cold). Muscles tighten up, and if it is cold enough you do not produce energy as quickly.
Seems feasible...any scientists out there who care to elaborate/ comment?
Not sure, cougie...we've been doing mid-late afternoons and the light has just been wonderful (we're very lucky in that we have the most fantastic scenery where we live), but I suppose the general reduction in daylight hours and intensity may be having an effect on our brains.....