I caught myself one time on the Astral Plane “writing down” the dream I just had – which means the “dream” must have been on the Higher Mental plane! I was confused – I came down to the Astral plane, and I thought I was wide awake and writing down my dream! But doing this, writing my dream in the astral plane, actually helped me a lot; because I recited the dream experience 2 or 3 times, with pictures in my mind, and trying to find the words for it – words which, probably, disappeared off my made-up astral notebook moments after I wrote them down!
Then I really woke up in the physical plane – sitting up in bed now, realizing I was confused, and now I “really am awake”. Then it was super easy to write down what I had just memorized in my notebook on the physical plane, that I always leave next to my physical bed.
I think the same thing happens when you meditate regularly. You eventually start meditating ON the higher levels too – which probably helps you reach EVEN HIGHER levels. I can actually remember a time many years ago that I “meditated” in the Astral plane, and popped immediately into the Mental plane. That’s one of 2 or 3 ways to reach the Mental plane from “way down here”.