Get as much rest as you can
It is common to feel tired or even exhausted during the first trimester. This is because your body is getting used to rapidly changing hormone levels. Get as much rest as you can, although this can be hard if you're working.
Try to get to bed early at least one night a week. Even if you can't sleep until much later, relaxing with a book or soft music will help you to unwind. Turn off your phone and forget about work. Once your baby arrives, sleep will be so precious. So enjoy it while you can.