CPAP Freedom??
I didn't know that having too much pressure can make you feel tired.
But I have a question. Why are you adjusting your machine when it is already auto adjusting? I know my machine is set to 6 when I first turn it on and then it auto adjusts all night. Is that what you're talking about? The starting pressure?
Yes, if your pressure is too high for you then you can start having apneas (including centrals) again. Since my pressure started out so high, I've needed to slowly adjust it down. Normally the pressure range is a 4-5 difference, so 12 - 16 or 17. I find the narrower the range (14-17 for example), the better I do. Originally my CPAP pressure was 14. I found I didn't do well with just a straight pressure, hence my auto CPAP. I also found that since my prescribed pressure was 14, I definitely needed 14 to start with. Now that I need less pressure, the starting pressure still needs to be pretty accurate so I won't have events.
From the sounds of it, with a low pressure of 6, you might be able to get rid of your machine soon if your OSA is due to your weight. My DB's mom and aunt both have sleep apnea and both aren't overweight. So for them it's genetics.