Seasonal variation in effect of spa therapy on chronic pain.

Strauss-Blasche G, Ekmekcioglu C, Leibetseder V, Melchart H, Marktl W
Chronobiology International
The Journal of Biological and Medical Rhythm Research
Volume 19, 2002 – Issue 2

https://www.tandfonline.com/doi/full/10.1081/CBI-120002878