What I write is based on reading I've done and discussions with my pulmonologists (sp?) over the decade plus since I was diagnosed with Sleep Apnea and put on a CPAP. Some of what I know may be out of date.
There are four levels of sleep. In level 4 most of the muscles totally relax, including those of the throat. Sleep Apena is caused by the throat totally closing on the transition from level 3 to level 4. It is normal for the throat to close some, but abnormal for it to close totally. In order not to suffocate, the body goes back to level 3, but as soon as the oxygen deficit is caught up it goes back to level 4. A person with Sleep Apnea (PWSA) can go back and forth hundreds of times an hour.
My pulmonologist tells me that there are some other minor disturbances to the sleep cycle for PWSAs.
Most PWSAs don't totally wake up or restart at level 1. In fact most PWSAs, when asked, think they are getting a good night's sleep.
A PWSA has a throat that is either too narrow and/or too flabby. The later is why people who are seriously overweight are much more likely to have Sleep Apnea. People who are extremely overweight (in the 500 lb range or more) can and have died of Sleep Apnea. At some point their throat don't reopen and they suffocate.
Snoring and thrashing while asleep are both indicators that Sleep Apnea might exist.
There are several therapies for Sleep Apnea, some of them are:
CPAPs work by pressuring the throat and keeping it open during level 4 sleep, allowing a normal night's rest. A ventilator forces air that is a constant amount over ambient air pressure through a hose to a nasal mask. The mouth naturally stays shut while the mask is delivering the pressurized air. It is possible though difficult to talk with the mask/ventilator on. There are carefully sized openings in the mask where exhaled air and the pressurized air exit.
CPAPs masks and hoses need to be cleaned weekly, and have their filters changed monthly.
When I was diagnosed there was only one kind of CPAP - one that delivered the same pressure all night. There are several manufacturers - I don't think it makes much of a difference which one you have. Exhaling against the pressure is a lot of work. The muscles of my chest and diaphragm were very tired each morning when I woke up.
Exactly what pressure is needed to keep the throat open is determined in the sleep lab, with a CPAP in place. They try a range of pressures over that part of the night. If one loses or gains a significant amount of weight, it necessary to go back to the sleep lab, and find out what pressure is now needed. It's wise to use no more pressure then is necessary to keep the throat open.
Several years ago, variable pressure CPAPs became available. Again there are several manufacturers. The variable models sense when your throat starts to close, and up the pressure from a minimal amount to the level the PWSA needs. When you go out of level 4, the pressure is reduced again. It's a lot less effort for the chest muscles.
My pulmonologist told me that more people successfully use the constant CPAP then the variable one. The varying air pressure wakes these people up. But some people can only adjust to the variable CPAP. The variable CPAP also only applies as much pressure as needed to keep the airway open. The variable CPAP has been better for me.
This kind of trial and error is part of the therapy process. There are several kinds of nasal masks. And several sizes of each. And some have spacers of different kinds that can be used. And several kinds of head gear - the straps that hold the nasal mask in place. It may be necessary to try several combinations to find one that can be worn successfully. A combination that is both comfortable enough to fall asleep and stay asleep with, and that has a good seal against the face - so no air escapes between the face and the mask.
It's also possible, that a heater/humidifier will be needed in the winter. Not all PWSA need one, but if CPAP use becomes difficult in dry and/or cold weather, ask for one. A heater/humidifier also need weekly cleaning. And you have to regularly refill it with water boiled for ten minutes.
The goal in CPAP use is to adjust to wearing one all night, while getting a comfortable night's sleep.
If you can't use it all night, use early in night is better then late in the night. Why? One naturally has more level 4 sleep earlier in the night.
Sleep occurs in cycles that are roughly 90 minutes long. Level 1 is REM sleep where dreaming occurs. Normal sleep has little time spent in levels 2 and 3. The first cycle is mostly spent in level 4. The last cycle mostly in level 1. With level 4 tapering off and level 1 increasing over the intervening cycles.
It's important to stay in touch with one's sleep therapist during the adjustment period. A number of things can happen, beyond getting the right mask and head gear, that should be reviewed with the sleep therapist - that can indicate a successful adjustment to the CPAP, or that further equipment changes are needed.
It's also important to give a CPAP a good long trial. It can take weeks to months to really get use to wearing one.
She might want to take the day off after her sleep lab night. She will probably NOT get a good night's sleep in the sleep lab. I advise she stays up that day, and go to bed early - the same way one handles jet lag.
I haven't looked for web based resources for Sleep Apnea. 7 years ago there was both the American Sleep Apnea Association and the National Sleep Foundation. If you can't find them on the WWW, I can send you the old addresses.
You might ask on the USENET newsgroup sci.med for more information and WWW URLs.
Check out the National Institutes of Health's Sleep Apnea web site
This is a good book:
Phantom of the Night: Overcoming Sleep Apnea Syndrome and
Snoring-Win Your Hidden Struggle to Breathe, Sleep, and Live
by T. Scott, Md Johnson, Jerry Halberstadt, Colin E., MD Sullivan
Paperback reprint edition (February 1996)
New Technology Pub
Dimensions (in inches): 0.55 x 10.97 x 8.55
www.amazon.com has it. www.mxbf.com might turn up a cheaper used copy. I have the original 1993 edition.
Successful use of my CPAP made a large difference in my life. Changing over to the variable CPAP made it even more comfortable.
If you have any other questions, now or later, please ask.