Your body runs on an internal clock called the Circadian Rhythm. When you fly across multiple time zones quickly, your internal clock stays in your home city while your physical body is in a new one. This mismatch causes Jet Lag.
Jet lag isn't just being tired. It includes digestive issues, brain fog, and irritability. Traveling East is generally harder than traveling West because it is harder for the brain to "advance" the clock than to "delay" it.
By respecting your body's need for sleep and light, you can conquer any time zone transition.