When you can't breathe through a stuffy nose, it's hard to fall asleep. If you have a cold, sinus problems or allergies, you have difficulty breathing when you lie down. Gravity helps solve problems and can also help alleviate it. Raising your head on several pillows may make breathing easier. It is also helpful to humidify the air and change position.

Gravity
Your nose produces quite amazing 1 to 2 quarts of mucus every day. Nasal mucus keeps the area moist and captures bacteria and small particles in the air. During the day, nasal mucus flows down from the back of the throat and is swallowed. When you lie flat, the mucus does not slip easily to the back of the throat. You will also swallow less frequently at night, so mucus builds up behind your throat and nose, making breathing more difficult.
When you lie down because of the flow, the blood flow to your nose will increase without being hindered by gravity. If you already have a stuffy nose, this enhanced blood flow will increase the stuffy nose.
Low Humidity
Mucus needs to be kept moist to easily flow to the back of the throat. Breathing low humidity air can dry the nasal mucus, causing it to thicken or solidify. Humidifying the air you breathe at night instead of overheating your bedroom helps prevent your nose from drying out while you sleep.
Allergies
If you only have a stuffy nose at night, you may have an al to know something about your bedroom. Substances in bed sheets, carpets or dust mites may cause an allergic reaction to the nose, accompanied by an increase in nasal congestion. Visiting a doctor for an allergy test can help determine the cause of nighttime allergy symptoms. Over-the-counter antihistamines can also help, but don't take them regularly without talking to your doctor first.
Deviation from the nasal septum
The nasal septum splits the inner half of the nose. Your nose works best when the septum is centered inside the nasal cavity. However, the American College of Otolaryngology reports that approximately 80% of people have a skewed or slightly skewed nasal septum. When you are lying around, the side of the nose may be compressed. If your nasal septum deviates and compresses the nose more open, it may accumulate mucus on the narrower side. Lying on the other side of you,Lifting your head may help ease the nighttime congestion of the deviated nasal septum. For severe cases, surgery is recommended to correct the alignment of the diaphragm.