New to meds, unusual effects

im 29, I was diagnosed last year, I got on stimulants in December, 30 MG adderall xr, at first it was great, I was able to get all kinds of stuff done, I finally was getting more than 4 hours of sleep again. ive been getting drowsy after taking my dose for the day, im a night shifter and I work 12 hour shifts so my day/night clock is almost exactly backwards from the "norm" unsure how relevant that information is. as of writing this, 1845 local time, I took my dose over an hour ago (around 1730,) and im just feeling extra sluggish, and I slept rather okay today, 5ish hours of off/on, (typical for the last 2ish months, im known for getting much less and still being alert though) is this a habit thing? its making it hard to perform my work duties.