i personally think 8 hours all at once is better! the long 8hrs gives your body time to settle and heal, rather than short periods of time where you might not get this. it also means less REM time during the 4hr naps!
I don’t know if sleeping four hours at a time would give you all the rest you need. I do know that I’ve only ever felt rested when I’ve slept for a full night.
Depends on what tends to make you feel more energized… but studies show that if you have a "power nap" in which you don't enter REM stage of sleep (deep sleep), so, 15-30 minute nap in the middle of the day, would help you be more energized than 4 hours twice a day. But again, depends on what works for you.
I believe yes, because you would complete the cycle and your body will feel restored after those 8 hours, but splitting the amount of time you sleep is not going to let your body fully charge, also is not the same to sleep 8 hours from 9 pm to 6 am than sleeping 4 hours from 12 am to 4 am and then sleep from 12 pm to 4 pm, the cycle on the first one is going to be better because you are resting when almost everything is quiet and darker than normal
Both are acceptable for optimal health. When asked yesterday how much sleep we need, Dr Daniel Amen, famed researcher and Neuropsychiatrist of Amen Clinics, answered, “Seven hours.” You want enough that your brain can cycle through the various sleep stages but not too much that contributes to other heath problems. As he explained, sleep is necessary to detox your brain. It is like giving your brain a bath, allowing it to be cleansed from all the day held as much as possible. Maybe more importantly what we might focus on for optimal brain health instead of two four hour sessions of sleep verses eight, etc, is “Am I doing all I can to ensure I am practicing optimal sleep health? Do I turn off digital a few hours before sleep, start dimming lights, etc?” to help induce sleep. But also looking at yourself as an individual and talking with your MD or another professional to ensure you have appropriate understanding of what your individual needs are such as a supportive sleep yoga routine, apps or recordings or training that provide/s sleep stories and meditation, brain wave/breath/neurofeedback that helps one transition to sleep, etc. Also, neurological and cardiac disease can come into play with sleep and restoration effectiveness. If you find yourself struggling to sleep or not feeling restored after a good nights sleep, speak with a professional to learn how best to optimize your sleep and do not go beyond 48 hours without sleep without calling your MD.
The short answer is YES. The brain has a huge amount of “jobs” that it does throughout the time we are asleep (read “Why We Sleep” by John Sackville), which cannot be performed if only achieving 4 hours of sleep.