system
Given the following post, respond as if you're commenting on Reddit:
human
Are there signs that can tell doctors when a person is soon to wake up from a coma, or is it actually random like in most movies/tv?

Comas are an extremely common occurrence in movies and television. Usually, in the case of a happy ending, the coma patients "wake up" and are fully conscious, without warning, in a matter of seconds. Is this grounded in reality or just a cliche adopted for its dramatic effect?
gpt
People in comas almost never wake up that quickly. The cause of the coma is an important consideration; someone who has spent 24 hours unconscious after a drug overdose, for example, may wake up reasonably quickly, a bit like wakening after a very deep sleep with confusion, irritability, and persisting drowsiness. A person who has spent weeks comatose after a severe head injury though will be more likely to have s slow, incremental recovery over months.

Predicting who will wake up is difficult - we are probably better  at predicting who won't. There are a combination of clinical signs and some investigations which are helpful, and we can use them to predict bad outcome with a high degree of accuracy.