normal oxygen saturation is usually between 95% and 100%. sounds loke you have sleep apnea and are stopping breathing periodically through the night. a doctor should prescribe a c-pap machine for you . its a machine that forces air into your lungs as soon as it senses you are not brathing properly.
I agree with streetdoc, it certainly sounds like you have Obstructive Sleep Apnea. I was diagnosed with OSA about 25 years ago so I can understand what you are going through. While you are waiting to see your doc again you might try sleeping on your side if you are a person who sleeps on your back. When I was first diagnosed i rented a C-PAP machine and was not to crazy about it so I opted for the surgery to remove the uvula and part of my soft palate (the soft tissue at the back of the roof of your mouth where the little 'punching bag' is.) I had another overnight test at the sleep clinic and I still had multiple episodes so I ended up having to use the machine after all. They can be a drag to get used to but trust me, after a while you won't even notice you are using it. The masks have really improved over the years and mine is quite comfortable. If you go with the machine you will need to wear a mask and turn on the machine when you go go be at night and leave it on until morning. A technician will set the amount of pressure your doctor recommends (they will test you once more to make sure the pressure is good). You will choose from a variety of masks which will strap onto your head with an attachment that will provide an air tight seal around your nose or in the nostrils themselves. The machine will blow air up your nose through the mask - you need to keep your mouth shut when the mask is in place or all of the air will just blow out of your mouth. If your mouth is shut then the air will force the tissues in the back of your throat to stay open. Most machines these days have a sensor that tells when you are exhaling and the pressure will go way down while you breath out and then go back up to the proper setting when you breath in. You should keep the machine on the floor or at least a foot lower then your head while in bed, otherwise, the hose could fill up with water droplets during the night that will rund back down the hose and into your nose. Not pleasant.
Like I said, it can be a drag getting used to the machine but you will and you will feel a lot better in no time. No more morning headaches, no more sore throats and dry mouth in the middle of the night and especially no more feeling like you could fall asleep while standing in a line up at the checkout, or while driving or while in a boring meeting or during a movie, etc. etc.
Good Luck and all the best to you :)