Good evening (it's evening for me here in the UK). I am no expert myself in this area, but I too have experienced something similar when you suddenly wake up and it feels like someone is there or has just walked out at an exceptional speed.
From what I understand, it can be many things. For a start, when we are sleeping, our mind is in a completely different state. If we're very tired the night before, our mind/body is working harder to do whatever it's supposed to do (clear out the toxins in our body and mind), therefore if we wake up suddenly (like you did with an alarm clock), it's possible your brain was perceiving something to be there.
On the other hand, you may have temporarily been in sync with the correct visual range to see angels. (Please forgive me Allah if I am wrong).
I would advise reading Ayat-al-kursi before sleeping every night. If it is making you feel uneasy, perhaps you could ask a family member to wake you in the morning.
I hope I haven't said anything wrong. If anyone knows better, please feel to correct me.