-after a period of a few days, I began seeing unbiden images. This is, to say the least, unnerving at first. After a few minutes of hard focusing on the nothingness behind my eyelids, I began seeing things that were not products of my conscious imagination: people unknown to me would literally walk into view, look at me, and walk away. I would see streets and buildings unfamiliar to me. Tube stations, and the like.
-after a few more days, I was able to interact with these scenes and people.
Thank you, JD Thompson. This is an excellent description of what I have observed all my life upon falling asleep. For many years I was searching for someone who is also aware of these visions. Some people call them hypnagogic images but I am not sure they always mean the same thing. In some sources they describe hypnagogia as directly related to sleep paralysis but from my experience they are not necessary dependant on each other. I am usually able to observe these places and people before becoming REM paralyzed. In some instances I was even able to talk and describe what I was observing. The most staggering about them is their superb 3D realism and the level of detail, although, they are never anything I have ever seen in my life before. I have to say that I find these visions more enigmatic than any other type of dreams. After decades of "looking" at them almost every night, I'm still in awe, and still unable to find a good explanation for how the brain is able to render such ultra-realistic animation in real time.
Also, I strongly suspect that such visions might be responsible for some encounters, which some people describe as alien visitations. As I mentioned, I'm certain that these images can occur before sleep paralysis. For this, IMO, some experiencers so adamantly and probably justifiably object the sleep paralysis hypothesis.
I have experimented with lucid dreaming for several years and I have successfully induced a highly realistic lucid dream of alien encounter (without the negative aspects). The difference from a regular alien dream is that one is fully conscious even if she doesn't realize that is dreaming. That means that the dreamer can consciously observe, reason, make decisions, and after that remember all details of the dream. The events enfold in a regular linear time which additionally adds to the realism of the experience. I can easily envision how a semi conscious dream can be interpreted as a real alien encounter.
From what I've learned in the years I practiced it, there are several different techniques to induce a lucid dream. The easiest way for me to become conscious quickly and when I need it is the following. I go to sleep at regular time. Before that, I set my alarm clock to wake me up after only 4-5 hours of sleep. When I wake up, I must get up from bed for about 25-30 minutes. In that time I think intensively about conscious dreaming, read something in a book or on the internet about it, or simply smoke a cigarette on the balcony and think only about how I am going to realize in the dream that I am dreaming and what I'm going to do in the dream - if I chose to fly, where to fly, who to meet, what to experiment with. I don't think "If I become lucid." I think "When I become lucid, I will..." After that I go back to bed, turn off the lights and fall asleep again. The first minutes it seems like it's impossible to fall asleep any more, but only in a short time I'm already dreaming and at some point I realize that I am dreaming.
The simple explanation for why this usually works with most people is that our body needs about 7-8 hours of sleep every night, while the brain needs only about 5 hours. When we wake up the first time, our body still needs to rest, but our brain becomes alert enough to regain consciousness and remember what it's supposed to do.