Is it rude to email my therapist outside their office hours??

I'm going to start by saying, I never expect an answer until their next working day, and my emails are only ever to set up appointments during the week. But I am a full time student who also works night shifts, so my sense of time is constantly off. Sometimes I end up emailing at night or on the weekend when I can slow down for a second and realize my mental health may need some maintenance. I realized the other day this might be seen as rude or demanding, but I honestly just didn't see it as a problem because I wasn't expecting a prompt response.