John Gill Commentary Luke 22:45

"And when he rose up from his prayer, he came unto the disciples, and found them sleeping for sorrow," — Luke 22:45 (ASV)

And when he rose from prayer
The Syriac version reads, "from his prayer", having finished it; and the Persic and Ethiopic versions read, "from the place of prayer", or where he prayed:

and was come to his disciples ;
to the three, which he had left about the distance of a stone's cast:

he found them sleeping for sorrow ;
on his account; for he had signified unto them, how exceeding sorrowful he was; and they might perceive by his looks and gestures, the anxiety and distress of mind he was in, which must needs affect them; and besides, he had given them some intimations of his being to be betrayed by one of them, and of his sufferings and death, and speedy departure from them; and because of these things, sorrow had filled their hearts, and this had induced heaviness and sleep upon them; (See Gill on Matthew 26:40).