Not exclusively ancient Greece or Rome. I'm talking about any/all soldiers before guns became a major factor in warfare.
You might be interested in threads from the FAQ section on "Post Tramatic Stress Disorder before the modern era":
How did the soldiers of antiquity/medieval times deal with the inevitable PTSD type issues that come from brutal hand to hand combat? - 147 comments, over 1 year old.
More examples from all across time, with analysis and source criticism present in several of the comment threads.
Was PTSD any more, or any less, prevalent amongst ancient and medieval soldiers than todays soldiers? - 16 comments, over 2 months old.
This thread delves into a discussion of the merits and flaws of an often cited work on PTSD amongst pre-modern warriors.
Did Ancient peoples suffer from Post-Traumatic Stress Disorder or similar psychological issues? - 55 comments, over 2 years old.
There's a wealth of examples drawn up in this thread though not as much analysis.
Is there any information on Post-traumatic Stress in societies in which warfare was looked at in a more favorable light (e.g Sparta)? - 41 comments, over 2 years old.
The topmost comment draws examples from the thread above this, but down below there's a source brought in to analyze pre-modern combat which results in a debate both about such occurrences and the value of the source.
Are there any indications of combat PTSD in societies like the Spartans, Khan's or Alexander's armies? - 31 comments, over 1 year old.
This thread narrowly focuses on Roman soldiers and thus is able to do strong analysis of the available texts and evidence in a way not done in the threads above.
Is there evidence of PTSD in ancient warrior cultures? - 14 comments, over 1 year old.
A few more examples ancient examples as well as dealing with a book on the topic of PTSD.
Did men of the past suffer emotional trauma from war and killing? - 6 comments, less than 1 month old.
This thread goes deep into the source criticism and interpretation when making judgements of whether or not pre-modern peoples were experiencing what would be diagnosed as PTSD in the modern day.
Did soldiers in the middle ages get PTSD? If so, was it different then PTSD now? - 83 comments, over 2 years old.
There's some debate in this thread whether or not the circumstances that people lived in during the Middle Ages made them more resilient or not to PTSD.
Is there any mention in medieval books and records from those times of what we now call PTSD in knights, soldiers, warriors etc? - 9 comments, less than 1 month old.
There's one large quote given in this thread about how clergy specifically cited the psychological toll of combat as a reason against it.