I heard you say once that we better synthesize protein that we eat before 10a.m. I am guessing that that varies accordingly with our usual waking up tube, right? A person that wakes at around 5 and a person that wakes at around 9 won't have the same time frame for better protein digestion, I assume...

The optimal protein synthesis based on waking time varies with circadian rhythms. According to the research discussed by Andrew Huberman, muscle tissue is better at synthesizing protein early in the day due to the expression of the circadian clock gene called BMAL. And while the time frame mentioned in one study was between about 5:00 AM and 10:00 AM for humans, it’s important to note that this doesn’t rigidly mean that protein cannot be synthesized effectively after that window. Different individual schedules and factors, such as resistance training, can impact protein synthesis as well 1.

Therefore, it seems reasonable to assume that for someone who typically wakes up at different times, the "early in the day" window for enhanced protein synthesis would adjust accordingly—as your muscles are primed to incorporate amino acids early in your day, not strictly according to the clock. If your main interest is in hypertrophy or maintenance of muscle, you'd want to ingest protein relatively early after waking and within a few hours to maximize synthesis. But, this would also have to balance with any personal intermittent fasting protocols or other dietary patterns 2.

For someone waking at 5 AM or at 9 AM, following the principle of early feeding as per their waking schedule could be applied, while still respecting that no food should be consumed in the first hour after waking if practicing intermittent fasting 2.