sorry for my late response i did not see your post before now.
im reffering to stocks and commodities trading (and all their trading methodes and channels)
its the time zone of the pacific ocean where there are no stock exchanges (only water no country) so the trading day of the world is 23 hours. new york closes as last and 1 hour later new zealand opens its stock exchange (1 hour lacking) depending on what charts you look your opening hours will differ but it should all have the same times for opening 4/6/8/12 hours candles.
even if its 3 am in new york it doesnt mean theres no trading. in china/japan etc people are trading us based stocks from dow and nasdaq. these trades go in as futures into the nasdax and thoe stocks and the dow and therefore when new york opens at 9am local time the prices differs from the closing prices of the day before. and the last 4 hours candle of the day is in fact a 3 hours candle because in the pacific the first stock exchange that opems for business is new zealand a hour after new york closed.
charting particurarly isnt done one one specific opening time of one specific stock exchange. the chart starts at exactly 00:00 central european time (paris frankfurt amsterdam milano) and from there a 4 hours candle is beeing calculated. so when new york opens the first 4 hours candle of the day can already be 1 hours old when your broker shows it to you (therefore opening gaps)
butvthat all is only a sidewalk. the important times you need to know are the opening times of europe (frankfurt paris london all opening at the same time) and new york. those are the volatile minutes/hours in which a lot of movement comes together. asia you can skip since 85% of the worlds capital is concentrated in europe and usa anyways and thats where the big money is moving.
this thou is not valid for forex as forex is a 24 hours market.
i hope this helped you.