I think that happens to all of us at one time or another. For me, it is a nightly occurrence, and I have to keep tightening that little slidey thing under my chin, but it works its self down later!! And I could be wrong, but I think sometimes it depends on the cannula you are wearing.
Maybe the others can come up with more ideas...
BJ

A little note - once the slider starts moving around on it's own - its time to swap out the cannula. The plastic has lost its elasticity and developed a memory that often isn't compatible with sleeping. Toss it and start on a new one. My daily cannula lasts about 10-14 days at best and my high capacity cannula on the treadmill is good for about a month. I believe it has to do with skin oil contact...

Hugs,
Dennis

A reference:

http://copd.about.com/od/fa1/f/changingthenasalcannula.htm

There are sites that talk about washing the cannula. Nope, not me. Far safer to toss them and use a new one...

Hugs

i have to wear mine tightened up under my chin when i sleep, but i wear it loose during the day.
besides tightening mine up at night i also clip the line to my shirt about waste level.
that keeps the line closer instead of just "dropping" straight off my face. (italso keeps it from wrapping around my neck on those 'restless' nights )
i too notice that mine gets loose after awhile as i "fiddle" with it. i wear it loose just sitting at the computer during the day, but if i'm up doing things or excercising i wear it a bit more snug & of course sleeping i wear it snug under my chin. so i think it just gets stretched out like dennis said.
i was told to change my canula's once a week & the long lines every 3 to 6 months.

directhomemedical.com/westmed-comfort-soft-plus-cannulas I hardly ever have the problem since I bought some of these soft cannulas. They are more comfortable too.

rcaro1= the link didn't work.

i'm interested. i tried some soft canulas once and loved them in the winter as they didn't harden up, but those i had an even harder time keeping snug. do you have some better ones???

http://www.directhomemedical.com Hopfully this will work, this is where I got them and they seem to work better for me.

TY! that link worked
& those look different because the ones i had didn't have "the curved" nose piece that i like. and these ones say they do.
rcar;
& they stay snug with the little slide thing, even if i "adjust it" up & don't during the day/night?

thanks again!
hopefully i can find ones i like before winter sets in again.

another question; my skin is getting so "paper thin" on my face, do the soft ones help to stop the irritation across the cheekbones where we get "the line"?