Does anyone know why this happens?

I don’t know how to explain this but I hope someone understands. Sometimes I am in bed and I know I have to do so many things and it would be so much better if I just get up and do them and I’m also conscious about time and being late for things but I just feel stuck in bed and I can’t get up, it’s such a weird feeling it feels like a paralysis or something. Does anyone know why this happens??