Do outdoor ferals sleep more in winter?

I have a cedar house for my feral, Muffin, on my porch and unlike last year, he's really made his home inside of it. It's been very cold and snowy since mid-November for most of the time in Western PA, and I've noticed that he's spending most of his time inside of his house, coming out to eat several times during the day, and only venturing off my porch for a bit in the evening. Did he always sleep this much during the winter the past two winters I've been caring for him and I didn't know it because he was sheltering somewhere else, or should I be concerned that he may be feeling under the weather (so to speak)? He has a great appetite and in fact is chubby. I worry about Muffin all the time since he won't come inside and won't go into a trap. Last February he got an upper respiratory infection that led to an eye infection and almost turned into pneumonia. A veterinarian prescribed an antibiotic for him for me to put in his food, or I'm sure I would have lost him. I'm pretty sure he had the Herpes virus, which can reoccur at any time, and I guess I worry about this with the bad weather. I estimate he's about 3 years old, but it's possible he's older. Is it normal for feral cats to sleep so much in the winter?

I think they sleep more.  My two outside kitties spend 80% of their time inside their little houses when it's cold.  I'd just keep an eye on him for signs of infections and get the antibiotics ASAP.

I worry myself sick about them, too.  But if Muffin is chubby and healthy, he's fine.

Hmm, mine are not full time outdoor, but I just let them outdoors for length of time they prefer as there is no way to make them come in before they are ready, but I can't remember seeing them sleeping for at least 3 months, they are always up to something, playing, exploring, eating, running, they just don't stop at all. I guess they have to sleep sometime, probably only then when I'm at sleep, but they do manage to wake me up every now and then when I'm not sleeping at other building, not sure where all that energy comes from.