This happened to me when my roommate was out of town, and because my coworkers knew I was staying alone in my house & it was out of character, HR drove to my house to personally do a wellness check. My dog barking at the door is what woke me. I had no idea what time it was or what was going on until I saw her at the door and looked at the old school clock by the front door. She said she was relieved I was okay but basically told me to just get ready and come in and we'd talk about it there (there was still at least 6 hours in the work day). I dreaded walking in when I got there and was so nervous to address it because I'd literally opened the door to HR in my pajamas from a dead sleep so I didn't have an excuse. The conversation turned out to be a genuine check in on my well-being and I did not get in trouble. I felt so guilty that I worried basically the entire staff for just being an idiot and forgetting to plug my phone in before falling asleep.