He needs to learn to do this while he's in his full body. i.e. the lake. He keeps exerting himself while in this mobile format of his. Or is it that he keeps pushing while in this limited remote function version of himself because once he reconnects with his complete body, the remote version he creates for himself that houses his consciousness automatically goes to sleep to recover?
I would imagine that if he was acting while fully connected to the lake, that he would probably not have the need to sleep. But that's just a general theory here.