Stephen said
Well I think we can infer from context that Mark was written for a community undergoing some degree of distress.  Jesus is providing an example of how to respond to such distress.  Whether this is a purely literary construct or reflects anything that might have actually happened is an interesting question.  How would the writer have known what happened?  The disciples were asleep and Jesus was arrested almost immediately afterwards.  

Stephen said
Well I think we can infer from context that Mark was written for a community undergoing some degree of distress.  Jesus is providing an example of how to respond to such distress.  Whether this is a purely literary construct or reflects anything that might have actually happened is an interesting question.  How would the writer have known what happened?  The disciples were asleep and Jesus was arrested almost immediately afterwards.  

Just because Mark said it in his narrative doesn’t mean it actually happened that way, so there is no way to know if the disciples really were asleep.  Or maybe Jesus had shared what he was going to be praying about with the disciples before it happened.

When Mark places the words “My God, My God, why have you forsaken me?” on Jesus’ lips, he is citing Psalm 22.  This does NOT mean that Mark’s use of the words of Psalm 22 necessarily need to be interpreted in the exact sense that the words were in the original Psalm 22.  The gospel writers were not necessarily staying with the “original sense” of bible passages when they cited them.  For example, in Matthew 2:15, Matthew cites Hosea 11:1 (“Out of Egypt I have called my son”) to give pedigree to his story of Jesus’ childhood time in Egypt.  But in Hosea, the word “son” refers to Israel, not to a child (let alone Jesus).  So we need to look beyond the literal meaning of cited passages by gospel writers to determine what those citations meant to them.