So, I finally figured out what cross-cover in the hospital means. During night call, the different teams "take care of" the other team's patients. So, for example, the other night, my husband's team was answering pages for 60 patients in the hospital. This is why sometimes he tells me that he got 45 minutes of "very interrupted" sleep. He may lie down for a few minutes, but his pager goes off continuously and he has to be ready to respond to various requests.
To me this seems similar to the first night in the hospital after delivering a baby. My little newborns ate often, woke up with burps or other funny noises, and were rolled in and out of the room for baths, weighing, etc. by the nurses from the nursery/ during that first night. In addition, the hospital staff came in about every 20 minutes to either check my pulse, draw blood, offer pain medications, massage my tummy, or just to ask if I needed anything - at 3 a.m. - even though I had been sleeping soundly before they came in. I was so, so anxious to leave the hospital after delivering each of my children, just so that I could actually sleep consecutively for more than 45 minutes at a time. Those were definitely the most painful nights I have ever experienced.
So, my husband is experiencing that every fifth night this month. Ouch. Just drawing that correlation has totally increased my sympathy for him and determination to keep the house quiet so that he can sleep after he gets home from his 30-hour shifts during call nights.