Jesus returned to the inner circle of disciples only to find them sleeping. He wakened them and addressed His question to Peter as the disciples" representative. His question contained a plural "you" in the Greek text. One hour may be a round number, but it is undoubtedly approximate. Jesus urged them to remain spiritually alert (cf. Matthew 24:32-44) and to continue praying for strength to withstand the temptation that He had told them was coming ( Matthew 26:31-35). Even though Jesus had told them they would deny Him, their failure could have been even greater. Therefore prayer for God"s sustaining grace in temptation was necessary. [source][source][source]
One of the marks of Jesus" greatness and His compassion is that even in the face of the Cross He still thought of His disciples in their lesser trials and encouraged them. [source][source][source]
The contrast between the flesh and the spirit is not between the sinful human nature and the Holy Spirit (as in Galatians 5:17) but between man"s volitional strength and his physical weakness (cf. Matthew 26:35). We often want to do the right thing but find that we need supernatural assistance to accomplish it (cf. Romans 7:15-25). [source][source][source]