How to take a mental health related leave of absence (immediately before quals) without revealing mental illness to advisor Recently due to burn out, my physical and mental health have been deteriorating to the point where I believe I need several months of leave to recover before I can be at a point where I can function normally again. I have been seeing a counsellor. However, now is a particularly 'bad' time to take leave because my PhD qualifying exams (first attempt) is very soon and in the month following, I have conferences/academic travels planned (which are great opportunities for furthering my career that my advisor has offered to me instead of to other students). Any one of these is enough exertion that I serious doubts that my physical and mental health will be recoverable afterwards, which makes me determined to take leave now, before it is too late. However, I am aware that having both these plans disrupted with short notice will not make my advisor or my department happy. Furthermore, while my relationship with my advisor is currently fine, it is not close enough that I feel comfortable confiding in him that I have a mental illness. His personality traits make me suspect that he might either not be particularly sympathetic/understanding, or he will be too afraid to 'break' me in the future. Therefore, I would prefer that the department and my advisor do not know that this leave of absence is due to mental health.

However, I need a compelling reason for the leave to be approved at this point in my studies and to have my qualifiers shifted to an unorthodox later date. My family are supportive of my decision for taking leave and have offered to invent some sort of family emergency which I can use as an excuse. However, my family are overseas, which is a fact known to both my advisor and my department (I am one of very few international students), yet I hope to be able to stay here during leave, where I have the support of both my husband and counsellor. We live close to campus and the counsellor is on campus in a small campus. So I am afraid that if I lie that I need to leave immediately for a family emergency, that during the time of my leave, my advisor/department secretary/chair will see me walking around campus and this might cause problems. 

Are there any potential valid justifications for a leave of absence which do not mean that I have to mention mental illness, or leave the country? I will also be discussing this with my counsellor, but perhaps someone here has a clever idea that I have completely missed. Also it would be helpful for me if people can provide me with context/comparisons for just how bad/uncommon it would be to 1) take a leave of absence shortly before a qualifying exam (from the view of the department and advisor) and 2) take a leave of absence that disrupts travel plans where so far no money has been spent (from the view of the advisor), so that I can have some expectation of the resistance I might encounter.
Have you considered asking for leave due to "urgent health-related issues" without providing more detail than you feel comfortable providing? There is no need to explain exactly what issues you are dealing with at the moment. It is perfectly sufficient to state convincingly -- perhaps with supporting documents from a medical doctor or other health professional -- that the issue is urgent and requires that you take leave as soon as possible. How you phrase this is something to discuss with your counselor.

Personally, I don't think it's reasonable, when your mental health is at stake, to agonize over what your adviser might or might not think of you. Chances are they will be understanding and appreciate that you come to them now and not later, when your health has deteriorated further and more work has piled up. By contrast, if your adviser turns out to be unsupportive or worse, it's time for you to look for someone else to work with! Also this is worth finding out sooner rather than later, so you may see this request as a litmus test of your adviser's qualities.

As another aside, brooding over other people's impression of you is a habit that isn't conducive to mental well-being. I suggest talking this over with your counselor as well, and finding a way to assert your needs and boundaries with confidence. It will come in handy later in your (academic) career.