One word: Hypnagogia

There are no clear definitions of when something is a dream, so when the other said that it was partially a dream they were very right.

Hypnagogia is something I experience every night as I meditate, There is no simple explanation of how to meditate although there is one of how to experience hypnagogia:

RELAXATION - Close your eyes, sit in a posture that is uncomfortable to fall asleep in but comfortable to be in, like sitting. Preferably in a dark room.

To keep focus say something out loud as you relax the body, I usually say something weird like alum-badedum. Loud and in a rythm.

After some time it will feel boring and I stop saying it, but say it for as long as possible. The key is to say it until you enjoy nothingness and silence more than an action and doing. Now say it mentally in your head and try to keep the focus as much as you can on the mantra, after some time mild hypnagogia will occur like you are thinking something weird like (toasters aren't for the professionals of tennis) o. O (I know but I think you will experience this as well).

Continue doing this and after about 30-40 minute of relaxation you will feel small vibrations in your body (don't focus on them though, it's not sleep paralysis! It's just your body' sensation of relaxation, you can still move...) But try to not put too much attention on this your focus should be on your mantra primarily.

At the same time you will also start experiencing the partially dream state called hypnagogia (hypnagogic auditory and imagery).

Remember that it can be occur earlier than 30-40 minutes even 5-10 minutes.

This was my simple definition of what hypnagogia is and how you can induce it. But Hypnagogia in itself is very undefined so let's try to define it even more, don't take the rest serriously, because I am not qualified to make a guess at all. It's just for fun!

Although here is my guess of what is actually happening, based on my current "knowledge" of brain chemistry.

After long time of relaxation and not moving, the body will decrease the aminergic system of the brain that governs your critical thinking and increase the cholinergic system which well right now can be one explanation to why we dream. aminergic system is (dopamine, serotonine and norepinephrine) and cholinergic (acetylcholine) not 100 % sure what each chemical does altough what we need to know for now is just the general effect of these system which I described above.

So perhaps the most clear definition of this yet is that the cholinergic system is slightly active in hypnagogia but even more active in REM sleep.

I hope this give inspiration and motivation.

Happy hypnagogic trips!