Blocked nose. The only way to tell is to have your nose evaluated by a board certified otolaryngologist,
Nasal congestion. Congestion is always worse when lying down. The blood-flow to the head (nose) increases lying down. You will also notice that when you are on your side, the down-side nose is most congested -some people have dust allergy and react to dust in the bed/pillows. You need an exam by ENT to determine if abnormalities like septal deviation (common) is involved.