In this episode of The Science of Sunshine, Dr. Anne Berends speaks with Prof. Timo Partonen, a leading circadian rhythm and Seasonal Affective Disorder (SAD) researcher at the University of Helsinki. Together, they explore how winter darkness disrupts our internal clock, why so many people experience winter blues or SAD, and how modern indoor lifestyles may be amplifying these effects.

Prof. Partonen explains the biological pathways linking light exposure to mood, sleep, metabolism, and energy — and why morning light plays a critical role. The conversation also covers proven treatments like bright-light therapy, as well as emerging research into UVA1 and near-infrared (NIR) light.