Remember that exhilarating moment in Awakenings when the frozen patients just wake up, catch balls in the air, sing, dance, and recall wanting to have sex? This isn’t that. In Coma, which follows four people in the first critical year after suffering head trauma, reality is a sad, frustrating existence, and there’s no big payoff. That doesn’t mean it’s not worth your time to get to know these patients, their families, and their doctors at the JFK Johnson Rehabilitation Institute in Edison, N.J. Tom, a 31-year-old sales manager, fell from a balcony. As he enters the MRI tube, his eyes open but not registering much, his fiancée relates to him the story of how he proposed. Sean, 20, was a college student in Europe when he was thrown from a bridge during an attack. His mom quits her job to watch each slow drip of his minimal progress. Roxie, 19, also a college student, wears diapers and cannot hold still but shows the most promise. Like Al’Khan, 26, a father whose prognosis is bleak, she was injured in a car accident. They are all in various stages of waking life, but they are not and likely never will be who they were. Their mothers are all pushed back into the role of wiping drool and sounding out words with their grown children. They’re the ones who break your heart. Filmmaker and Academy Award nominee Liz Garbus takes a fly-on-the-wall approach, and Coma features more observation than storytelling. She seems to want to give people their privacy and space while still leaving an audience who may have forgotten Terri Schiavo with a vivid reminder: If severe brain injury should happen to you, know what you want and make your wishes clear.