Hyperventilation causes an increase in volume of air into the lungs, via the airways, and this influx of cold dry air cools, dries and irritates the upper airways. They respond to this assault by swelling and creating extra mucus, both of which tend to narrow the airway slightly and impeding the flow of air.
Hyperventilation not only cools, dries and irritates, but it also increases the amount of germs, dust, pollen and other airborne pollutants that are dragged into the airways. The airways keep these things out of the body by increasing mucus production and chemicals such as histamines to capture and neutralise them. Histamine causes further airway narrowing by creating swelling and additional mucus production.
In order to get the air through the narrowed airways, the person needs to inhale with slightly more force, and instead of passively using the diaphragm, the stronger chest muscles may start to be used as well.
Water vapour is breathed out during the exhalation, and so hyperventilation tends to lead to dehydration, which makes mucus stickier and harder to shift so that it clogs airways a little more. It also makes us thirstier and more likely to wake up with a dry mouth, clamouring for a drink of water at all hours of the night or in the morning.
Hyperventilation causes a loss of carbon dioxide, and this can cause a problem for the body if the pressure drops too low. Death is a potential if the pressure becomes too low, so to prevent this very big problem from happening, the airways narrow even further.
Being the start of the respiratory tract, the nose it is the normal body part to use for breathing, and so it is the first part to narrow. When the air streaming through the nostrils suddenly runs into a narrowed upper airway, the air in this part is suddenly moving faster than usual. This is a bit like running a wide, silent river through a gorge. All of a sudden the water has to move a lot quicker because the weight of the water is pushing it through this narrowed riverbed.
As the air begins to move faster through the narrowed part, it jiggles the tissue more than usual, and this causes the snoring sound.