I'm coming out the closet...I am a nasal irrigation addict.
I have problems with my sinuses (I'm a martyr me! Ever hear me complaining about it? All the feckin time actually)
If you have a cold, allergy etc. give it a go. The further you bend over when doing it, (simmer :x ) the 'higher' the sinuses rinsed. if your foreheads congested bend over further.
It is a strange sensation at first, but really does help. Sonny has it spot on. Indians irrigate as a matter of course for health, hygiene reasons, maybe the dusty climate?
Go on! put some body temperature liquid up your nose, you know you want to!
Cheers