Every now and then, I am prone to experiencing hypnagogic hallucinations. I used to have very light and mild ones, such as seeing spiders crawling about on a web attached to my bed, only to have them slowly fade away into nothing moments after waking.
However, I have gone through periods where I would often have more intense hypnagogic experiences, usually consecutively each morning. These kinds would almost always begin with an intense ringing in the ears, which would rapidly crescendo and be accompanied by other strange noises. I would always feel a presence, at least one. Typically, this would only happen if I left my door open at night. Closing my door was a sort of psychological safety net, along with the bells hanging off of it. (bells ward off ghosts in japanese superstition, so it's just an extra layer of reassurance)
Of course, whether to view these figures as ghosts or not is kinda ambiguous to me. Seems to do the trick in calming my mind though and preventing such experiences- but I tend to keep it open out of curiosity.

In any case, it always starts with sounds. I mentioned accompanying sounds along the ringing of the ears earlier- usually this was in the form of a voice. Sometimes the voice would sound very muffled and distorted, though it would startle me by sounding like it's speaking right into my ear. Sometimes I would single out the voice of a girl, speaking a few lines to me in Japanese. Sometimes I would hear a kind of hellish wailing, or maybe it'd be mostly silent only to be broken by an abrupt shout, which seemed to turn into laughter. Regardless, I've experienced these hypnagogic hallucinations often after my 2nd time waking after sleeping in, and come to distinguish the various "characters" that appear during them. When this happens, I am almost exclusively aware that I am in my own bed again and awake all except for opening my eyes- and sometimes when I open my eyes, I get a brief but startling visual, such as once of a standing figure spasming near the foot of my bed. Oftentimes though, it's hard to tell if it's a false awakening or not.

So, that said, these experiences are pretty terrifying for me as they happen, as I feel completely and utterly vulnerable, but after the fact I try and write down as much as possible and more calmly contemplate it. My most intense series of this went on for around a month or so, but I haven't had such an experience in perhaps over half a year now, aside from very mild, almost half-started ones that I quickly shook myself out of.
The thing is, I basically learned how to exit these experiences at will, completely interrupting them and simply waking to my empty room, aside from residual visual side effects such as seeing static on blank white surfaces (this subsides after awhile). I think I've developed a habit of simply repressing them before they even start, which is rather a shame, because I feel that
1. They can lead directly into lucid dreams if I can discipline myself to remain calm until the "ringing in my ears" peaks
2. These mysterious figures themselves may be manifestations of things I'm not dealing with, repressing, and could help me identify them
3. Perhaps these figures are beings all on their own, a sort of emotionally charged spirit. I've observed that they reflect my own state of mind- if I lash out at them out of fear/anger, they change to become much more frightening in appearance. If I remain calm and serene, they simply go about doing their thing- they don't seem actually malicious or anything to me, just disturbing to the average person, maybe a bit mischievous.
4. I've heard that similar states of mind can lead into out of body experiences as well, and would greatly like to experience one.

It's been my goal of sorts to be able to remain calm, or at least be brave and expose myself to and endure a terrifying situation, because I feel there is a reason I am exposed to such things to start with.
I typically refer to these experiences as waking dreams, since these events seem to be transposed upon reality, at least during that brief half-awake half-dreaming state. I find that the more I acknowledge and think about them before sleeping, the more likely I am to experience a waking dream. I write this mainly just to have it on my mind more and out of a bit of curiosity what others have experienced or other speculation. I think talking about it will make it more 'relevant' in my mind.

As for anything else of note....these experiences can be incredibly difficult to tell apart from reality sometimes, because sometimes they will mimic people I know in real life. For instance, one morning I heard my mother stomping about the hallway and enter my room, nagging me to stop sleeping in and get out of bed. I grumbled something and opened my eyes, but was shocked to find absolutely no one there, and recalled that my mom wasn't even home at the time, but out on a business trip.

I also have a lot of other interesting stories but I'll hold off for a moment since I've already written out a wall of text here heh. Feel free to ask questions and whatever else!