Husband won't wake up!

My husband sleeps more soundly than anyone else I have ever met! We have been taking shifts lately staying up with the baby. He will watch her from 7 to midnight and I will watch her from midnight on until he gets up in the morning. The problem is that he keeps falling asleep between the hours of 7 and midnight and sleeps so deeply he doesn't wake up when the baby starts crying. Often times I will wake up to the baby screaming and when I go into the living room I find him snoring on the couch with her crying in her swing only about 5 feet from him! Does anyone else have this problem and any suggestions? And he does have sleep apnea but he wears his cpap once he actually goes to bed around midnight.