Could Sunlight Determine Stock/Bond Returns?

I’ve heard of some bizzare theories on stock movements, but here’s one that saw the light of day. (Yes, I kill me). Moneyquote:

University researchers in Toronto say they have found that bond and stock markets move in conjunction with the seasons, partly because some market participants are affected by seasonal affective disorder.

SAD, a form of clinical depression that affects people in the fall and winter, makes investors more risk averse, the study suggests.

Why not? It sounds more reasonable then Fibonacci numbers, used by followers of the Elliot Wave system.