Hi. I Would Like To Know Why If I'm Laying

Hi. I would like to know why if I'm laying in bed out of no where & all of a sudden I get this warm sensation inside my body every where.
The only thing Ivan compare it to is
It feels the same as when I have had contrast go into my veins for a CT Scan or MRI.
Once the warm sensation goes away after a few seconds then I get a tingling sensation for a while