A wonderful story. I loved Harry's withdrawal into himself. I can't see him interacting with too many people when he's so unable to express himself. I like that Severus is affected too, but in a different way. It seems ironic for a man that probably didn't have enough time in the day during the war to be unable to sleep.
I'm so glad that the two of them could comfort each other without being a magical cure. They're just enough for the other.
I also liked that Severus knew Harry better than Hermione--goes to show how much really changed.