<human>: So this is my first post to Reddit but the more I think about this the more it bothers me. I'm not sure if this is a "normal" thing so I defer to the wisdom of the internet for advice.

I'm a 21 year old female living alone in an apartment building. My front door has two locks, as most do-- the normal handle lock and a bolt lock. I never bother with the bolt lock, especially when I'm at home. 

I'm almost entirely nocturnal during the summer, so I was sleeping all day yesterday. When I went to leave the apartment later on, I noticed that the bolt lock was locked, which I am 100% positive I did not do myself. I also noticed when I got home that my thermostat had been changed to a temperature way below anywhere I would put it (but probably normal for most people-- I like to keep it warm).

I can only conclude that someone let themselves into my apartment yesterday, WHILE I WAS THERE SLEEPING, changed the thermostat, and left. Nothing else is out of order, nothing is missing. While the thermostat thing is new, this isn't the first time I've noticed the lock thing-- at least one time prior I have come home from class to find it locked. 

Now this may just be me being misinformed about landlord/maintenance ettiquette, but I'm pretty fucking sure that you can't just send people into apartments without at least letting the renter know about it, right?

What the hell do I do about this? It's really starting to creep me out knowing that someone can just waltz into my apartment and fuck around while I'm sleeping in the other room.

Give me a shortened version of the text
<bot>: Someone (assuming landlord/maintenance for my own sanity) lets themselves into my apartment for unknown reasons with no warning while I am not there/asleep