It seems unrealistic that Samson could stay asleep on Delilah’s lap while she gets a barber to come and has Samson’s hair cut. Is this simply explained by concluding that Samson must have been a pretty deep sleeper? That could be the case. But perhaps there is a better explanation, based on the context. Perhaps this instance was anticipated in Judges 16:1–3, where Samson is able to lift the gates of Gaza and carry them off without the guards waking up. There it was quite likely that their deep sleep was divinely induced. Now, interestingly, the tables have turned on Samson, where instead of keeping the Philistines from knowing events right by them, the Lord puts his very own deliverer to sleep.1
19 She made him sleep on her knees. And she called a man and had him shave off the seven locks of his head. Then she began to torment him, and his strength left him.