I have osa and have a cpap machine. its only on 7.5 rate at the moment. it seems to work and the mask is comfortable but i'm still tired the next day. what could be thereason?

Other issues?: Should see your dr. And discuss if you may have other health issues that may have to be addressed. Lifestyle changes, diet, weight, emotions and stress...See them.

Follow-up study: If you haven't already done so, consider getting another sleep study done with the CPAP machine in place. The study will show if the machine is properly treating your specific situation, and confirm that you are no longer experiencing apnea. Many people immediately feel more rested. Others, (me included--i use CPAP too) don't feel any more rested, but i know that is is better for me. Keep using.

If all else fails: Osa is a very real threat to the health and safety to yourself and the public. Many highway deaths are osa related, poor school or workplace performance too. Poor respiration is not a minor issue. If CPAP and all else fails, speak to a maxillo-facial surgeon, sometimes 2 jaw advancement surgery can make all the difference in the world. Bimaxillary advancement surgery.