Study indicates the brain is very different in the morning compared to afternoons.

That could be why, over the years, when I interviewed for jobs the best results were on morning interviews.

Another anecdote: a few years ago I had done data analysis for a client on their sales data and found out that the most relevant factor on whether a sales deal closed with a win was the time of the day, usually around midday, meaning that the conversation likely occurred in that morning.