Hello.
You might be experiencing what we refer to as Hypnagogic (transition to sleep) and Hypnopompic (transition to wakefulness) Hallucination. These are not uncommon. Some individuals also experience paralysis of their limbs while seeing images in the room. The sleep mechanism induces a physiological paralysis of the muscles during the stages of dreaming, so as to prevent body movements from happening. The transition periods between wakefulness and sleep can sometimes lead to the mind being awake for a while but the body paralyzed. You may not be experience the paralysis and so you can ignore this description of the paralysis. But seeing images is part of the hypnagogic and hypnopompic hallucination. You may consult your GP about this and perhaps get a sleep study done to find out more about your sleep architecture.
You might also find these conversations helpful.
http://ehealthforum.com/health/topic56376.
html
http://ehealthforum.com/health/topic39274_
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http://ehealthforum.com/health/topic103940
_20.html
Hope this helps.
Take care
Abhijeet Deshmukh, MD
(This post is for the purpose of providing medical information and is not a substitute for a face-to-face consultation with a doctor. This post is not intended to give or rule out a diagnosis, create a doctor-patient relationship or replace an existing one. I am not able to diagnose medical conditions online. Please consult with your doctor or a qualified healthcare provider for diagnosis and treatment options)