If I remember the rules correctly, at my college, anyone who is in your room has to be gone by 4 AM (pretty late in my opinion!) And if they are sleeping over, the person inviting them + the roommate have to fill out a form 2 days in advance. The roommate has to agree to the person sleeping over, so they can refuse to sign the form if it makes them uncomfortable.
However, people do break the rules all the time. One of my past roommates had guys over every now and then and I wasn’t cool with it, but I let it slide because I didn’t want to start problems. I know RAs who have broken the rules too, so it’s definitely possible. Just make sure your roommate doesn’t tell an RA or RHD because then you’ll get in trouble.
I would call the admissions office or housing office and ask what their policy is. I’m a college tour guide for the admissions office, and we’re trained on knowing this information, so someone should definitely be able to tell you.