She likes to sleep on surfaces that we might consider uncomfortable. This is one example. Another is sleeping on a soft bed across some cables that pass right underneath her.
Do you find that your cat does the same thing? As she has a double coat, the undercoat being a fine downy hair that provides great insulation, I believe that she likes to lie in cool surfaces that allow a bit of airflow around her body. Flat hard surfaces allow that.
I am not sure why she likes to lie over cables, though. This might be a throwback to her life as a new born kitten.