The question about will a soldier seek out help when they are losing sleep and exhibiting signs of PTSD. Probably not if they are still in the military, because the military has a deep ingrained belief that PTSD is a weakness.
Another thing to consider, soldiers in combat develop a powerful attachment to one another. The strength of this bonding overshadows all others, even family. First of all the degree of familiarity and closeness that extreme survival situations such as combat, brings people together to a height one has never experinced before. People have an instinctual need to feel a belonging such as in a herd where they feel safe.
A small combat squad that has experinced several fire fights develops a sense of oneness with each other, they have become one organism through the forging process of fight or flight. Due to the nature of killing and survival all of their other emotionality has become severed from their environment and channeled into the solidarity that soldiering brings. If one of them gets wounded or killed they all feel it through their connection of unity.
This herdness has supplanted all other attachments while people they once knew intimately have become foreign and strange. The family, friends and soldier feel this estrangement and all involved become unfamiliar and uncomfortable. Family and friends cannot understand what they have been through, so they seek others who do.
Some soldiers will long for that interconnectedness left in the field when they came home and reenlist or volunteer for another tour. Many soldiers find that their PTSD symptoms dissipate or vanish while back in the theater of combat, they have reentered the realm of survival, fight or flight and oneness with soldiering.