What is SAD.?

https://getpocket.com/explore/item/seasonal-affective-disorder-the-scandinavian-guide-to-surviving-the-dark-days-of-winter?utm_source=pocket-newtab  

SAD

https://getpocket.com/explore/item/seasonal-affective-disorder-the-scandinavian-guide-to-surviving-the-dark-days-of-winter?utm_source=pocket-newtab