Congestion of one side of the nose is accompanied by decongestion of t
he other side. This is called the nasal cycle. The nasal cycle does no
t seem to be present in all subjects and it has not been shown with rh
inostereometry. There are very few studies showing whether there are s
pontaneous day-to-day variations in nasal mucosal congestion and no st
udies showing differences in nasal mucosal congestion between morning
and afternoon. This, however, may be very important in studies coverin
g a longer period. In the present study, data from four healthy volunt
eers were recorded 18 or 19 times in the mornings and afternoons on di
fferent days. Measurements were made with rhinostereometry, a peak flo
w meter (PNIF) and by symptom scores. A nasal cycle was found in some
subjects. There was no difference in total nasal mucosal swelling in t
he mornings and in the afternoons and no day-to-day variation in the t
otal nasal mucosal swelling.