Mark 14:32-42 - What Jesus was doing while His disciples slept.

In the events just before Jesus was betrayed by Judas and eventually crucified, Mark tells us that Jesus and the disciples,
32 ...went to the olive grove called Gethsemane, and Jesus said, “Sit here while I go and pray.” 33 He took Peter, James, and John with him, and he became deeply troubled and distressed. 34 He told them, “My soul is crushed with grief to the point of death. Stay here and keep watch with me.” 35 He went on a little farther and fell to the ground. He prayed that, if it were possible, the awful hour awaiting him might pass him by. 36 “Abba, Father,” he cried out, “everything is possible for you. Please take this cup of suffering away from me. Yet I want your will to be done, not mine.” 37 Then he returned and found the disciples asleep. He said to Peter, “Simon, are you asleep? Couldn’t you watch with me even one hour? 38 Keep watch and pray, so that you will not give in to temptation. For the spirit is willing, but the body is weak.” 39 Then Jesus left them again and prayed the same prayer as before. 40 When he returned to them again, he found them sleeping, for they couldn’t keep their eyes open. And they didn’t know what to say. 41 When he returned to them the third time, he said, “Go ahead and sleep. Have your rest. But no—the time has come. The Son of Man is betrayed into the hands of sinners. 42 Up, let’s be going. Look, my betrayer [Judas] is here!”(Mark 14:32–42, New Living Translation, 2015)

What was Jesus doing while His disciples slept? Obviously, He was praying. 

If the disciples fell asleep, how did they know what Jesus prayed--in order to record it in the Gospels? 

Remember, Jesus was crying out in prayer. As they drifted off to sleep, they must have heard Jesus's cries. 

It's probable that He also prayed for them in line with his instructions: “Keep watch and pray, so that you will not give in to temptation...” (v.38a) 

Peter had been warned of a temptation to deny Jesus. With the warning, Jesus told him, “But I have pleaded in prayer for you, Simon, that your faith should not fail...” (Luke 22:32, NLT) Isn't it likely that Jesus would be praying this for Peter, who was sleeping just a few paces away?

Another account of Judas betraying Jesus is in John, chapter 18. But chapter 17 is a lengthy prayer. It's a strong possibility that Jesus continued such prayers in the Garden: that his followers would remain unified so the world will believe that Jesus came from God and understand that, "You love them as much as you love me." (John 17:23, NLT)

Lord Jesus, We can't stay awake indefinitely. Help us to discern when we should fight off sleep. Forgive us when we're not alert enough to pray against temptation (2 Corinthians 6:5, 11:27).  Thank You for praying when we do not (Romans 8:34), and that You still invite to join us in Your prayers. You died for us. May our selfishness die so Your people will live in the perfect unity of God's will for which You sacrificed Yourself. Amen.