Why do I sometimes wake up from a dead sleep and not be able to see? The lights are on and I don't get up too fast. Vision comes back after 5 minutes.

Its ok. In a young healthy person, this is nothing to worry about, unless you have some rare vitamin a deficiency, or other rare dystrophy.
Needs evaluation. This may be a simple problem, a so-called hypnogogic (technically hypnopompic in this case) sleep problem. Many people experience unusual neurologic phenomena transitioning from sleep to wake or wake to sleep. However, with the limitations of this forum, it is impossible to determine whether a more dangerous neurologic problem is present. See your doctor for specific diagnosis.