I sometimes enter a mental state that I understand is pretty uncommon, which I tend to think of as being somewhere between awake and asleep, although it might be better described as not even being on the same line/spectrum as them at all. To some extent it's deliberate, in that I can choose to do this, but only if the circumstances are right, and when the circumstances are right, it's become so easy that it's almost automatic.
This wasn't always the case. I sort of created this additional state for myself as a result of the combination of two unrelated things: a simple beginners' meditation exercise described in a book on Buddhism, and pointless "breaks" at work that seemed too short to really get any rest/relaxation out of, nevermind a real nap.
When I'm in this state, I am aware of the sounds around me, but they're just a sort of physical experience, rather than information getting analyzed & comprehended, unless I hear something that seems like it warrants attention and decide to turn my listening switch back on for that item. Even people speaking my native language (English) take on a funky dual nature in which the meaning doesn't invade my awareness spontaneously but is available if I feel like inviting it in, almost like a foreign language that fades from babble into English if I just start paying attention. I have thoughts from time to time, but mostly I just sort of pick them up, look at them, and put them back down so I'm back to not really thinking again for a while. Time seems to slow down significantly; I have enough presence of mind to remember to check a watch/clock/phone/computer roughly once per minute, but it feels like what five to ten minutes would feel like when I'm awake. Physically, I mostly feel nothing, although a mild general tingliness occasionally appears, or a sensation that I could call "floating" but actually seems to consist of multiple contradicting feelings of movement in different directions at the same time. Either one of those ends pretty quickly if I just open my eyes and move even a tiny bit, even if I don't come completely out of this state of mind otherwise.
I bring this up here because, whatever you call this state of mind, it does have a connection to the process of falling asleep. You could even make a case that all I'm really doing is stretching out the process and being aware of it, while also being ready and able to easily abort at any moment. When I am on the way from this state of mind to sleep, those thoughts I mentioned above, which I'm observing myself having almost as if from the outside, start to make less sense, or I don't recall what thought I had right before the latest one. On a few occasions, I've had, instead of thoughts, the beginnings of dreams, which I knew were dreams, knew meant I was asleep, and took as signs that it was time to get back to being awake while I still could.