I don't find any value at all in testing free testosterone, and since we don't even offer "free" hormone levels of any other steroid hormone (cortisol, estrogen, progesterone, DHEA, etc.) we don't seem to value that data in general. The problem with trying to use the bioavailable portion as a tool for decisions is those levels change very rapidly and in different tissues at different times based on "demand". They aren't stable and reliable, which is why we don't even bother measuring them for other hormones. In reality, we don't measure free T directly either - that is a "calculated" value based on total T, SHBG, maybe other factors - totally useless informaiton. 1500ng/dL is a good total testosterone level for most 65yo men, but if he's not seeing any good results you might increase total monthly dosing by 30% and try to get it to 2000 - as long as there are no cardiac concerns. If certain symptoms persist, you would presume they are due to other causes. Sleep apnea is certainly a common cause of a lot of the same symptoms. If effective CPAP (using a device he will wear, which makes a good seal, and the mechanics of CPAP are all working as they are supposed to) isn't helping, then neurological causes need to be pursued. It's the brain that decides when we breathe and how much, so that's where need to look if the physical mechanics are all supported. Chemicals are the first and greatest consideration - paying attention to all chemicals intentionally taken into the body, trying to avoid environmental toxic chemicals and promote elimination of them. Opiates and sedatives directly suppress breathing and can lead to death from neurological sleep apnea essentially. There are a lot of other chemicals that contribute to this problem on a spectrum. Light pollution is another main issue - eliminating all electrically-generated light forms (candles and other forms of fire are fine) within at least 30 minutes before your desired bedtime is necessary for some people to sleep well.