Pre-Dream Half-Sleep: Please Explain to Me? Part II

[shafri]

apart from my experience in Part I (sorry i'm not allowed to provide link to the thread, i'm a 3 days member), i usually had another situation during my pre-sleep state. when i closed my eyes, we usually see black, right? but sometime suddenly a flash of light similar to a spark or lightning or like somebody taking your picture using camera with the flash ON while you are closing your eyes. with the sound of explosion, gun shot or sometime just a "pop", the feeling is so real that at the beginning i experienced this, i even get up to search for the light/explosion source around my house and outside the garden, but none, and i usually sleep in dark room where no light source can get in. can someone explain?