My 6 year old's son nose gets blocked when he goes to sleep. wakes him up. why is this?

Environment: It is likely that dust or other irritants in the air of the bedroom contribute to nasal blockage.Sometimes a sensitivity to dust mites that accumulate in pillows can be a contributing factor as it can in the bedding. There are allergy shield pillow and bedding covers available to help reduce accumulation but a new pillow may also be needed.

Nasal congestion : Could be several reasons such as allergies or uppercut respiratory infections are a few examples