Sometimes when I am lying in bed with my eyes closed, something in my brain will suddenly shift into a altered state of consciousness. My whole brain feels like it's shaking back and fourth very rapidly and I loose sense of gravity and body. I don't hallucinate or anything, but it's really uncomfortable. I can make it immediately stop by opening my eyes, but if I keep them shut, the experience continues. It's actually kind of terrifying and interesting at the same time.
I can describe the loss of gravity as when you spend a lot of time underwater and can't tell up from down. I often feel like I'm doing an underwater backflip. It's uncomfortable and disorienting. I lose any sense of my limbs/body and can't really move them. As soon as I open my eyes, everything is perfectly normal again.
I can generally "tap into" this state as long as it's quiet and I'm lying down and relaxed and also have my eyes closed. It doesn't matter if I'm feeling sleepy or not. I've found that it's much more intense if there is white noise in the background, like a fan or a motor running.
The first time it happened to me it was really scary. But then I began to let the feeling totally consume my body and it was actually rather fun. But then it became extremely uncomfortable. I've not experienced any pain when in the bouts, but if I remain in the state for long amounts of of time (long being more than 7 seconds or so) it becomes unbearable and I have to open my eyes. I've never been able to stay in this "trance" for more than 10 seconds or so without opening my eyes, but I have no desire to.
This sensation can be annoying and scary. I've been experiencing this for about a year now. I've not had any head injuries or anything that might be the cause of it. It's never been bad enough to want to go to the doctor, but I have no idea what causes this, or what it is really, so if anyone has any ideas, please help me out. I'm a 21yr old female.