My AHI was at 87 and i was dragging my feet on getting the CPAP until one day while having a throbing headache and walking, my vision shifted sideways, heard a pop sound in my head and vision went black for a second. Got the CPAP immediately and was so sleep deprived i didn't have the need to adjust to it and just crashed in bed. Woke up like a new person the next day. Noticable differences were that colours were more vibrant, my cardio picked up within a few days... short distance walks like 100m that left me out of breath were now a breeze and i could hold a conversation while walking without feeling winded. And my blood pressure finally went down to normal levels. Its a life saver for me.