You probably have poor blood circulation in your limbs. If you often times find your fingers and toes cold throughout the day and especially at night, even with clothes on, then the blood is probably not properly circulating through your hands/feet. It isn't too serious, a lot of people have it. I have it. It is really annoying because no matter how many socks I wear my toes always freeze at night.
I have bought wool socks. They look dorky I know...but they help a little. That is really the only solution I have found for it other than to wrap an extra blanket/sheet around my feet at night. My hands I just tuck into the sides of my pants...nice and toasty =)
I also have poor circulation in my fingers and toes. It tends to be worse after eating certain food. In my case, a faecal stool analysis revealed an extremely high count of streptococcus bacteria. This bacteria, when in the gut, processes starches in our food and produces a toxin called Hydrogen Sulphide, or H2S. This toxin can be responsible for bad circulation, amongst other things like brain fog.
Poor circulation can also be caused by low blood pressure, raynaud's phenomenon, diabetes, and maybe even vitamin D deficiency.
Keep wearing the socks. Insulation will help keep the heat in.
Better still, electric blankets are awesome - the heat will expand your capillaries and increase circulation will reduce the discomfort of the cold.
It's because socks aren't thick. They're usually just a thin layer or cotton and that isn't really designed to keep something warm. Maybe reduce how cold they are but not to warm. You'd need thick wool socks if you want warm feet. That or just wrap a blanket around your feet when you sleep. that's what I do
This happens to me all the time :o Right now for example. So I stole some of my grandma's fuzzy socks that she knitted or something and I wear them over my normal socks (which is like 3 pairs) and my feet are nice and warm :) So just get awesome grandma socks.