How long does it take for you to start feeling tired?

[Joe Biden 2020]

I wake up between 5:00 and 5:30 every morning, and feel drowsy between 10:00 and 11:00 am while sitting in front of my computer at work, but get a second wind as the afternoon rolls along, then start getting tired to the point of no return around 7:30 in the evening.  That usually puts me out by 9:30 or 10:00 most evenings.  So, I'm up for generally 16-17 hours a day, so my worst times are hours 5-6 and hours 14-17.  Usually about 9:00, I start yawning uncontrollably and thus am usually in bed within the next hour.

Weekends are different stories, though.  I get up at 5:30 on Friday's, but can stay up until 12:30-1:00 am Saturday without too much trouble and still get up around 8:30 on Saturdays.  On the flip side, there are weekends where I'm in bed by 8:00 pm, it all depends on what I've done and how tired I am.