Pilots call the wee hours of the morning the "window of circadian low." Unless you routinely sleep during normal daytime hours (for a few weeks at least), the c

Pilots call the wee hours of the morning the "window of circadian low." Unless you routinely sleep during normal daytime hours (for a few weeks at least), the circadian low still nudges your brain and body metabolism toward a lower-energy state EVEN if you are fully rested up until that point. https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%20120-100.pdf https://www.faa.gov/documentLibrary/media/Advisory_Circular/...