The world is a big place. When it is daytime in one place, it will be nighttime on the other side of the world. Every time the Earth makes a full rotation, which takes 24 hours, countries will undergo cycles of day and night. This creates distinct time zones from one part of the world to another.
The jet engine has made long-distance travel fast and affordable. This means that a lot of people will find themselves traveling to different time zones, quickly.
Our bodies operate according to the circadian cycle, which is a kind of biological clock. These clocks help to dictate how our bodies function, but traveling between time zones quickly can leave the clock out of sync. This is a phenomenon known as jet lag, which can come with a range of symptoms.
Symptom #1: Waking Early
Most of us need around 8 hours of sleep every night in order to be fully fresh the following day. This can vary from person to person, and some of us also find it easier to get to sleep than others. Regardless of how long you need, those of us who are fortunate enough will sleep all the way through until it is time to wake up.
This pattern can be completely thrown out in people that have jet lag. Our internal body clock can wake us up even when we have not had enough sleep. This leaves us tired throughout the rest of the day and feeling as though we need to get back to bed.