Why is a high dose of GHB dangerous?
At a high dose you can lose consciousness or pass out. There is a difference between sleep and a coma. If you pass out of GHB, you are in a coma. It can be a light coma. Someone will still react to painful stimuli or when calling a name. Or the coma could be severe. A person no longer responds to painful stimuli. It is difficult for a layman to determine how deep a coma is.
In extreme cases, there may be respiratory arrest. This is life threatening. Read here why.