I rember I did a short stint doing night work. When I started everyone told me how hard it is to adjust and that I should try some coffee. I don't do caffine so I turned it down. People weren't happy with me thinking I wouldn't pull my weight. Honestly adjusting was so easy. Caffine has two effects. It makes you amped. It also makes it so you can't feel sleepy (two different things). The inability to feel sleepy lasts a long time, so if you do coffee any other time than right in the morning you are going to fuck your sleep (sleep quality is actually effected over multiple days from having caffine), but it's going to essencially lock in your sleep schedule because you are going to be wanting to go to sleep as long as possible from your morning coffee. That means you lose the ability to adjust. That also means you lose the ability to sleep on demand (with full quality) when you have an opportunity which you can't afford to turn down when you are changing schedules. This also means killing caffine will help reduce redeye when traveling. You should instead give up caffine a week before traveling so that your sleep will be more flexible once you do travel.