What's the best way to be quite active in managing US stocks? Due to the time difference, I find it really hard to keep up efficiently with the price changes without killing my sleep?

Buy VOO or IVV.

Buy, don't sell.

Hold ultra-longterm.

Watch the results once a month.

Don't panic. Keep cool.

Don't: buy options, single stocks, leveraged products, never.

Sound like you are a trader not a investor.

If you are a investor, in fact i think being based in the Pacific continent is a pro. You got ample time to analyse things that are happening in the asia/europe market before making a prudent market order prior US market open

You have to question yourself if you're a trader or investor. If you're an investor, day-to-day price fluctuations wouldn't bother you so much. But if you're a trader, then you'd be more likely to pay attention to technical signals - moving averages etc. But at the end of the day, its about keying in your buy/sell price that you have worked out and just going to sleep. If the order isn't filled = not the right price to buy/sell

It is very tough as a day trader, most of the market actions happen at 10pm, 2am and 4am SG timing.