I have experienced similar things over the years. Because my own experiences are not scary or alarming, I don't bother with needing a diagnosis. I too have heard the knocking etc. Sometimes I think perhaps it might be an angelic presence protecting me, by waking me up from dreaming. I also 'see' spiders sometimes when I wake up, very big, fast moving ones on the walls that I know are not 'real' so this also does not bother me. I think they maybe a spiritual guide, when I am in the process of changing personally, a period of personal growth etc. I used to often see 'real' spiders, actual real spiders, whenever I had made a big life decision. And saw them as conformation from the natural world. Depending on your beliefs about the world, you may be hearing things from between different dimensions or times. The veils between the world may be more obvious to you that to other people. You may be highly tuned in to the natural world. If the messages bother you seek professional advice, otherwise perhaps try and find your own patterns and meanings behind the sounds you are hearing. Best of Luck. Embrace your unique qualities.