Before we delve into technicalities, let's ponder over 'sleep' from your personal experience.
Try to recall your sleep patterns over past couple of days.
Try to recall last night.
After you went to bed, how soon did you fall asleep.
What were you thinking while lying down on bed. Do you recall few moments before you dozed off?
What were your last thoughts or feeling before dozing off?
Do you recall any dreams from yesterday night?
Did you wake up in-between the night? Do you recall moments immediately following your waking up?
Do you recall the time you woke up in morning? What did you do immediately upon waking up?
What were your immediate thoughts or feeling upon waking up?
Have you ever received a prophetic dream?
Do you get repetitive dreams about anything - especially any fear?
The above questions are to trigger a specific process in your mind - to bring sleep and dreams into your awareness. To give importance to them.
Unless you give them any importance or contemplate on them, the true journey will not begin.
We can read about science and existing research from several sources on net. But the real research happen within the laboratory of your own mind. It's when you question and ponder over them, that life will start unraveling the mysteries of sleep and dreams to you.
Do spend some time answering above questions - you may like to make a note of them in a journal.
I highly recommend taking up a blank workbook - title it "Adventures in Lucid Dreaming" and start taking notes as we progress.
These notes and journaling will go a long way in your success with this course.