I'm just going to throw this out there...it may be way off base. I have ferrets who would live in burrows in the wild so domestic ferrets need a black out space to sleep during the day. They wake up and play at dusk and dawn. If I launder or take the thick blanket off the top portion of their cage my female will start losing fur from the tail up into the abdomen and back. Once they have a dark space (or darker space even) the hair grows back. I learned this a couple of summers ago and never have the top portion of their cage uncovered during daylight. It's open at night.
I have no idea if a nocturnal animal would react the same way but if he doesn't have a place to get complete darkness during the day, could this happen to SFS's?
That's all I have to offer, hope you get some answers!