Is there a harder time of day or day of the week to play?

I’m currently rated around 800–900, and I’ve noticed something very strange. When I play late Friday night into early Saturday morning, the level of my opponents feels dramatically higher than usual.

In over 4,800 games, I had almost never faced certain openings. But in a single session during that period, one opponent played the Slav Defense, and another played the Alekhine Defense. These are not openings I normally see at this rating range.

The games also felt much more precise. My opponents made fewer blunders, played more solid positional moves, and generally felt stronger than typical 800–900 players.

However, when I play on Sunday, especially during the day, I sometimes win 10, 15, even 20+ games in a row against players with the same rating range.

This makes me wonder:

• Is there a known variation in player strength depending on the time of day?

• Are stronger players more active during certain hours, such as late at night?

• Or is this just psychological perception and variance?

I’m curious if others have noticed the same pattern.

I have started tracking what time of day I play a game because I was curious to find out whether I play better at a certain time of day compared to the rest of the day. I started doing this only a few days ago and I need to continue doing this for several months before I'll have data that are statistically meaningful.

I'm not really looking at what day of the week it is (although that could be added). Performing better at a certain part of the day is probably normal, based on chronobiology and the existence of chronotypes.

Playing when you feel at your best and avoiding going on a tilt (for example by briefly analysing each game immediately after playing it) should also help.