@victorhugo - I feel for you, as I have gone through similar struggles myself. My suggestion is be careful and go slow - don't make drastic changes all at once. Here's an excellent book by sleep psychologists that might at least serve as a guide for your self-experimentation:
https://www.amazon.com/gp/product/158333534X/?tag=pfamazon01-20, by Michael Terman Ph.D. and Ian McMahan Ph.D. Or if you want something more academic,
https://www.amazon.com/gp/product/019958785X/?tag=pfamazon01-20, by Steven W. Lockley and Russell G. Foster; however, this is more technical & has less do-it-yourself information.
Beyond that, I have a few specific comments on what has been said already in this thread:
victorhugo said:
I've looked into the research, and like I previously mentioned, spliting sleep cycles into a two separate sessions typically works better than sleeping it all in one go.
Please list some cites that back up this claim. I am skeptical, for two reasons: 1) I'm not myself aware of any literature within sleep medicine that supports such a claim; and I have read a great many more papers than most people, being someone with several different sleep problems himself. Also 2) by chance I mentioned the "two sleeps are a normal pattern for human beings" idea to the sleep psychologist who is treating me, and we briefly discussed it; he dismissed it as more an academic fad than a proven claim.
More specifically, this claim you're repeating tends to be driven by anecdotal speculation by various academics that somehow, prior to the invention & widespread distribution of artificial lighting, Europeans in particular relied on a "two sleep" pattern in which they would sleep for some hours, then be awake for an hour or two socializing or doing other quiet things, then go back to sleep for the second time. My sleep psychologist says there is no real literature to back this speculation. Further, he cited the following study, in which several currently existing pre-industrial societies were examined for their sleep habits in the absence of artificial lighting. Perhaps surprisingly, all of these peoples delay going to bed after dark, just as we do - so this habit is evidently not caused by artificial lighting. as the two-sleep advocates tend to claim; and none of these people practice prolonged periods of wakefulness during the sleep period. Here's the cite: Yetish, Gandhi, Hillard Kaplan, Michael Gurven, Brian Wood, Herman Pontzer, Paul R Manger, Charles Wilson, Ronald McGregor, and Jerome M Siegel. “Natural Sleep and Its Seasonal Variations in Three Pre-Industrial Societies..”
Current Biology : CB 25, no. 21 (November 2015): 2862–68. doi:10.1016/j.cub.2015.09.046. Here's a link to the full text:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4720388/
Quite different than the "two sleeps at night" pattern is the siesta pattern, in which a couple of hours are lopped off nightime sleep and replaced by the siesta; this pattern is much better studied. It doesn't seem to be what you're proposing for yourself, though.
CalcNerd said:
What if your body/brain needs a minimum of 5 hours to actually make use of the sleep cycle?
To my knowledge, @CalcNerd is correct. This is something else my sleep psychologist said: It is indeed true that if you
do wish to divide your nightly sleep into two sessions, each session needs to be long enough to be effective. Two or three hours is not enough; I don't remember the exact cut-off but it's at least 4 hours. For whatever reason, a siesta period at mid-day can be shorter than that; I don't know why.
victorhugo said:
I get sleepy in the afternoons and always end up procrastinating, so I end up being more productive at night.
Yours is a common experience. However, as others commenting in this thread have already stressed, there are many factors involved for things like getting sleepy in the afternoons, procrastinating, etc. You need to be more scientific than this to really understand your sleep.
jamalkoiyess said:
8 hours is just an average, most people only need 7 or 6.
This is untrue and a common myth. In fact research has consistently shown across many decades that "most people" who get only 6 or 7 hours are chronically underslept. The fact is, most of us do better with 8 hours of quality sleep, and few of us get it. We are just so used to not getting it, we think we can get by without it & don't realize the ways in which our health is already suffering.