Some people have periods at night when they seem to mstop breathing - have large gaps between breaths - and this can lead to continual tiredness. It may be that they are just getting insufficient air.
Two relative inexpensive ways to avoid minor probems of this nature are ways of keeping the nostrils open at night.
One means is the wearing of a semi-rigid sticky band across the lower part of the nose so that the spring effect keeps the nostrils open.
The other is to use nostril inserts to keep the nostrils open at night.
Bothe of these methods have helped me.