From personal and similar experience, I found with my Drs. help of course, that the most likely culprit is the low blood pressure, which in itself isn't necessarily a bad thing up to a point.
I've always had slow heart rate (48 to 51) and low pressure (115/48), but within the last couple of years my hands have become very cold. My Doc deciphered the problem (not Reynaud's, which usually manifests in blue fingernails, I'm told) as intentionally losing 20 pounds (weight, not money here in the U.S.) which lowered my blood pressure by a bit even more.
I have several pairs of gloves conveniently stashed here and there which does seem to help. Haven't had to wear them to bed yet, though.