I have had a number of experiences where I wake up but my body is still asleep... its very disconcerting as I can see my room and its contents but my eyes are closed and I am aware of what is happening, but I can't wake up. Usually it takes a few minutes before I am "released" from such situation, and I can't help it but feel scared (imagine being trapped in your body and unable to wake up forever!). Whenever this happens I would chant DS' mantra and also put his image beside my bed, it reminds me that I am protected and I feel calm, and fall into peaceful sleep.
I am not sure if my experiences have anything to do with negative spirits / energy (I googled it and there is such a thing called sleep paralysis, which many cultures believe is due to spirits/demons... I can't remember the scientific explanation off hand now because it is less intriguing hehe) but I do believe that having faith in DS protection when I am in distress does help a lot in calming my mind and let go of negative notions/energy.