I am never sure if I have them when I am asleep since I am asleep and don't know. Sometimes I wake up with them and other times they come on moments after I wake up. If I am startled awake like when my cat jumps on me I feel them come on very fast the more severe and then they go away. This makes me think that adrenalin/stress adds to their strength. I agree about the phrenic nerve that it is somehow getting an altered signal on how to function during sleep/awake transition. Thank you for your reply