DH and I are arguing because he keeps telling DS to "lay down" when putting him to bed. I eventually cracked and hissed "it's LIE DOWN" in the middle of the night. He's accepted that I'm right (but has not accepted that it matters).
BUT if you can lay down your own head upon a pillow, can you lay yourself down upon a mattress? My feeling is that whilst it might be grammatically correct it just feels wrong 
Is he right? Can you lay yourself down?
Would you ever actually use that phrase instead of lie down?