How does he do that?

Jared has this ability to fall asleep at the drop of a hat. Tuesday night, I was tucking the boys in and Jared commented that his blue blanket wasn't at the end of his bed (fleece blanket with silky edging I made for him as a baby, which isn't the most prized of lovies any longer, hence it's place at the END of his bed, but he likes knowing it's down there). I told him I'd go find it and bring it back to him. I walked to the other end of our house, found it on the couch, stopped for a quick glass of water, then headed into his room with the blanket. He was sound asleep already. Last night, I tucked the kids into their beds, came out sat down at the computer. I'd BARELY sat down when Connor came out of his room saying he had to go potty (yet again!). I helped him use the bathroom and wash his hands and put him back in bed and looked up into the top bunk to say goodnight to Jared again, but he was OUT. And so it goes, night after night. He's asleep within a minute or two of laying down. How does he do that???