My wife complained that I stopped breathing during sleep now and then. I realized that when I wasn't breathing I was actually holding my breath. I was dreaming about being under water when I held my breath. Most of the time I was panicked dreaming that I'd fallen through the ice and could not reach the surface because the ice was too thick to push through. I read up on dream control and used it to stop dreaming about being under water or at least to realize I was in a dream state and did not have to hold my breath. Fine now.