Studies at Stanford and Duke of parents whose kids spent time in the NICU found that they often exhibited signs of post-traumatic stress disorder--including nightmares, flashbacks, and panic attacks triggered by beeping alarms--long after the kids came home:
[A]lthough none of the fathers experienced acute stress symptoms while their child was in the NICU, they actually had higher rates of post-traumatic stress than the mothers when they were followed up later. "At four months, 33 percent of fathers and 9 percent of mothers had P.T.S.D.," Dr. Shaw said.For Parents on NICU, Trauma May Last [nyt]
It may be that cultural roles compel the men to keep a brave front during the trauma to support their partners, Dr. Shaw said, adding, "But three months later, when the mothers have recovered, that's when the fathers are allowed to fall apart."
Abstract: The Relationship Between Acute Stress Disorder and Posttraumatic Stress Disorder in the Neonatal Intensive Care Unit [psychiatryonline.org]
Posttraumatic stress symptoms in mothers of premature infants.[nih.gov]