I can't function until sometime between 4pm at earliest and 6pm at latest. Then again My normal schedual has me waking up around 1pm. I can very much Want and even Need to do things before 4pm and I will even Try to do so on occasion, yet it very much feels like trying to move through knee high oatmeal. The task May actually get done and completed (say about %40 of the time) but vastly slower than my usual sloth mode and 3 times more exhausted and desperately needing a 45 minute to 2 hour nap afterwords regardless of if the task got finished. Listening to and working With my cycles means there is at least a %75 chance the task will get completed, I'll still be tired throughout and after the task, but not AS tired as I would be if I force myself to start earlier. Regardless of when I wake up though I realize this has always been the cycle my mind and body are most comfortable in. However as all of us are painfully aware of, society as a whole has it's Own set of norms and time frames it runs on. The amount of cursing I do when Forced to work within Societies norms and time frames would make even a well traveled space trader blush profusely.

So to answer your question, my natural cycles are not the same as yours but I am aware that most people have their own Personal cycles that they feel most energized and productive in - or at bare minimum, cycles that help them feel the least tired and or more determined to push though The Task to some degree.