In 1884 the International Meridian Council suggested a zero point and a way to match clock time with the position of the sun. It looked good on paper but hasn’t always made sense. We can see in the map below that times zones can be chaotic,
Time zones are often social instruments rather than logical ones. China should have five time zones but only has one. India should have three but only has one. In my own state of Oregon a portion of the east of the state is more culturally and socially tied to Idaho than Oregon so shares Mountain Time Zone.
Anyone who has traveled internationally knows that jet lag is real. When I was travelling regularly to Japan I still remember leaving Tokyo at 7 PM Saturday night and arriving in Portland 10 AM Saturday morning which does a great job of messing up your body clock. For some reason flying west is much easier than flying east. I have never heard a good explanation of this. I was always in pretty good shape when I got to Japan but I was always a zombie for two or three days when I returned.