It's not by meditating you reach the astral plane. It's when you sleep, or actually when you're just about to. Meditation is about grounding, finding peace within and slowing down our breath. All in all, to become more mindfully present. Nearly sleeping and dreaming, however, enables you to let go of your thoughts and emotions, and just relax, letting your body breathe its natural way. That's when you easiest reach the spirit world.
Sensing things that are intangible and invisible are a little like dreaming. In fact, it's right before you go to sleep, or when you're beginning to wake up, it's said that your soul is loose enough in your body to meet others'. To travel a little outside of your body and then re-enter. To be in a fluid state of mind, makes it possible to both have access to the spirit world, and a great source of creativity. Take a nap, and you will soon remember what it was you set out to do and had forgotten about or come up with an idea to solve a problem, or even what to write, if you're a writer like me looking for inspiration. I like the resemblance of baking. We must let the dough rest and rise before it becomes ready for the oven and to eat. The same thing applies with creativity. We do our research, such as interviews or read up on a specific subject and then let it sink in for us to understand, question and develop into an idea.
More thoughts about this can be found in the Bible, as shared here.