I’ve observed that too. Significant moves up or down tend to happen around UTC 21:00. That’s 5am where I am, and an awkward time for me. Still early in Japan and Korea, but many are already up. 5pm in US east and Americans are fully alert.
I’d often convert some BTC to stable coin Nubits at Bittrex, and USDT at Binance, before I go to bed. This way I won’t be too upset should the market be red when I wake up.
The average price of BTC - there’s a significant difference between the one listed at CoinMarketCap and WorldCoinIndex. The latter is often $100 lower. Apparently these sites don’t have the same markets connected to their system.