The mental health figures were supplied in response to an Official Information Act request about mental health issues.
Chief of Defence Lieutenant General Rhys Jones said in his response that NZDF recognised "maintenance of the mental health of its members is of high importance due to the activities inherent in military service".
However, he also conceded that it was more difficult for military staff to get help when they were on deployment. "The immediate availability of psychological support can be constrained by the nature of parts of the deployed mission."
He said an example would be forward operating bases and "the relatively austere nature of such outposts".
Corporal Hughes took his life while off duty at Romero Forward Patrol - the sort of base referred to by Lieutenant General Jones.
Labour's Defence spokesman Phil Goff said the rise in the figures showed there was a need to learn lessons about mental health care for troops overseas.
He said the trauma of experiencing young mates being killed would have impacted strongly on serving staff and showed NZDF needed to consider its focus on psychological support.
"I think the public and the serving personnel and their families need to know the defence force have got it right around the culture of safety," Mr Coleman said.
Mental health
NZDF personnel with psychological conditions
2007: 59
2008: 72
2009: 94
2010: 123
2011: 134
NZDF staff assessed for psychological repatriation from Afghanistan
2008: 0
2009: 5
2010: 9
2011: 8
2012: 19