Many people find the crossing hard at bedtime. Either the body is not tired enough, or it is so tired that it drops straight into deep sleep.
There is a better moment: the middle of the night. After four to six hours of sleep, the body still wants rest, but the mind has had enough to be clear. Thinking is quieter. You are drowsy without being lost.
The method is called waking back to bed. You set an alarm for that hour. When it wakes you, remember at once why you are awake. Get up and move about slowly for ten to thirty minutes. Stay drowsy: no bright screens, no chores, no news. Sit quietly, or go over your intention.
Then go back to bed and begin the crossing of page 56. Or simply lie still and repeat, as you drift off: I will come out of the body.
This is not a practice for every night. Use it once or twice a week, on nights when the next morning is free. Sleep matters, and the rest of the night still belongs to the body.