I have had a lifetime of sinus problems.  At different intervals in my
life, i have had some serious episodes of drowsiness.  These episodes
have happend in high school classes, in business meetings, and while
driving.  I learned through trial and error that cigarette smoke and
red wine are triggers.  I have also had to deal with these drowsy
episodes as a delayed reaction with an allergen trigger. I have been
punished in classes for "dozing off".  I have been laughed at for the
same reason.  35 years ago I rolled a car after an evening at a bar
exposed to a lot of cigarette smoke and drinking the equivilent of one
glass of red wine.  I live in Denver.  I used to go up to the mountains
to ski.  I would drive home and would have extreme drowsy attacks.  The
culprit was hot spiced wine - a Burgandy with spices and sugar.  This
was not enough to get drunk but more than enough to have serious drowsy
issues.  I have been fired from jobs for "nodding off" in business
meetings where several people were smoking.  The positive is that I
have a lot of control over a lot of these issues.  I don't go into
smoky bars by choice.  I avoid red wine.  Other than a few allergens
such as some pollens in the summer months, I am relativly drowsy free.
I do carry some afrin and a nasal steroid in my car when I need it.  If
I have a drowsy episode while driving, I get off the road.  After 20
minutes, the symptoms pass and I continue driveing.  I have not had to
pull over for several years now because I can use my nasal sprays
before I have any severe symptoms.