Why can I only sleep at sunrise?

For the past few weeks I have only been able to fall asleep at sunrise. What bothers me the most is that I have not changed my eating habits or have any more stress that I ever have had which is what my doctors have told me what might be the top causes of my sudden change in sleep pattern. I have also been having really bizarre dreams that are heavily based on reality, as if i am experiencing another day within the day I have already been through. The only difference is every thing looks slightly distorted like looking through clear, stationary water. I am not sure if that has any relation to my change in sleep pattern but I thought it might be relevant to someone.