You could ask this guy. I'm saying nothing of the "worthiness" of credentials, just that he's studied and written quite a bit about sleep. Here's an article HERE.

He advocates for biphasic sleep (longer 7-9hr "core" + ~30min nap) and thinks it's how the body prefers to sleep.

Maybe write to him and include your data and see if he can offer you any input? He may very well get contacted by people in your situation and have some information about what helped them? I do know that he advocates for people having trouble to attempt "free running sleep" if possible -- basically sleeping when tired, waking when not. Obviously this is impractical for most, but if your situation allowed for it, you could really give a shot to shutting out distractions and just sleep and keep a log.

Anyway, not much of a help, but I stumbled on his work a bit back and thought I'd at least toss it out as a suggestion. At least contacting him might prove helpful. See his "Apology" link near his contact information. He sounds tough to get a hold of. I'd make it a "provocative" subject line, like "Need serious sleep assistance. 5 mos of data attached."