Hello and hope you are doing well.
In the initial phases of the sleep cycle and while awakening, we tend to be more conscious or alert. If we study the brain waves at these phases they tend to show the alert wave pattern, this could cause the awareness. If it is not interfering with your sleep schedules you don't have to worry. If it persists or is troublesome consult your doctor for assessment.
Hope this helped and do keep us posted.
Found this for you.
"A person may wake up and find himself unable to move or speak as if he is frozen. He also may hear footsteps, see a ghost-like creature, or feel someone sitting on his chest. Throughout the history, people considered this phenomenon as work done by evil spirits. However, the modern science can explain the terrifying event as a Sleep Paralysis."
some readin on sleep paralysis:
http://serendip.brynmawr.edu/exchange/node/1740
Several things could be going on, you could be experiencing night terrors, perhaps brought on by the added stress in your life, or it could be sleep apnea that can cause a variation of different symptoms. If this continues you should seek out advice from a medical provider.