Ok, so what is the big deal about sleeping bags, especially in the Southeastern US between March and October? Why not a blanket or quilt? If I do end up looking for a bag, what is a good, lightweight model that packs down small? Money is a big issue right now. Are second-hand/used models ok?

I expect to use the bag 3-4 times per year, mostly in summer months, and probably in Alabama. I already have a bag that I got at a secondhand store, but it weighs 6.25 pounds and is huge. I didn't buy it for backpacking, anyhow.

Thanks in advance.