I keep Waking up naked

I wake up very regularly with my lower half of my body naked. Even though when I go to sleep I’m clothed in shorts and underpants. But 3-4 times a week I wake up with my lower half naked and fully hard and super horny. I get that waking up hard is normal but it’s the fact that my lower half clothes keep coming off, I’m sure I’m removing them but I don’t know how it’s happening.

Has anyone ever had this? And how do I stop waking up like this?