Experimenting with something.
Picked up an o2 concentrator (yeah, I know you cannot abort with one). 
Going to try sleeping all night with a nasal cannula on at a flow rate of about 5lpm. 

Thought is that... I get hit in the night regularly.... 2x-3x every night without exception.  I have no doubt it is caused by decreased breathing rate and maybe a bit of snoring / apnea.  Guessing the resulting trigger is low o2 saturation in the blood.

Thus... greatly increasing the oxygen I am uptaking during the night may reduce or eliminate sleepy-time hits.

Will post some results when I have them.
Hate to post anything tentative... but night one with it I had 1 hit.  I have not had only 1 nighttime hit in 40 days.   

Specifics...
Invacare Platinum XL 5
Got it for $150 bucks.  Guy had a storage unit full of the things.
Warning light indicates it is only putting out 73%-82% o2.  Optimum is 87%-95%.  This indicates it is time for a compressor rebuild.
Parts kit for a rebuild is around $20.  Already ordered.  Should be a piece of cake to do... just a bunch of seals and such. 
Can also send the compressor to a service house for rebuild at around $90.    

Not getting my hopes up.  I always wanted one of these things for the home gym when on the treadmill or elliptical anyway.

Any luck Lobster?  Curious minds want to know!   

I understand why people say that the concentrators don't work, but I have been one of the lucky one's I guess because that's what I use at home (two of them attached together).

Tore the unit apart yesterday.  Rebuilt the top end of the compressor... which was not really needed as it was in fine shape inside.

Checked the unit for air leaks... found two fierce ones near the plastic 4-way valve.  Epoxyed over them.  o2 purity reads much better now.

On a side note, these are not o2 concentrators so much as they are nitrogen removers.  They work by sieving out the 80% of the air that is nitrogen, leaving you with the other 20%, 90%-95% of which is oxygen.  Quite interesting internally... not much to them.