Jet Lag
This may have happened to you when you went on vacation and after traveling over a few timezones, you found yourself unable to sleep; it was because of jet lag. However, despite how tired you may have been then, you should be happy that this reason why you can not sleep is just temporary.
This disturbance in your circadian rhythm is specific to traveling, and it will not appear at other times. The bad thing about it is that it’s generally accompanied by headaches, fatigue, and sleepiness during the day, and it can even lead to insomnia if the change was a bit too drastic and you’re already having problems with your sleep schedule.
Don’t worry though, you can easily fix jet lag in most cases as your body catches up to the timezone and you adjust to the new time with one hour for each timezone you crossed! The drawback is that you will have to adjust when you get back home as well, but you can rest assured that you will be able to sleep afterward.
