hello and welcome to HCM,
The clogging of the nostrils is a normal phenomenon which is a part of what we call the nasal cycle
. Furthermore, physiologically which nostril will become blocked depends on so many different factors such as the time of the day, position of the person and the presence of any local abnormalities such as DNS
So this varies from person to person and for each it is unique.
However, if you feel your nose block is more and bothering you in such that you are not able to sleep then you need to consult an ENT to rule out any other local problem
Dr Sriram Nathan