At the end of my first year of my PhD program, I was completely, utterly, and magnificently burned out. I had one final seminar paper left to turn in, and it was due at noon that day. My anxiety was so out of control that I couldn't bring myself to start the paper until the day before it was due, and I pulled an all nighter (my first) to finish it. I finished it, went to campus to print it, only to find that my endnote software had crashed and I had to redo the bibliography by hand. it was late, my professor noticed, and commented. I felt no relief, only more anxiety. I walked across campus to the campus counseling center, past the undergrads relaxing on the Diag feeling the joy I wished to feel, and requested a same day, emergency appointment. Within a week, I was seeing a therapist off campus (my condition was "more severe" than the short-term counseling services felt comfortable handling) for appointments two days a week. Outside of my partner, who lived with me and was blessedly not an academic, I told no one and attempted to keep up with the work load of my summer research job, exam list preparation, and archival research trips. This was, in retrospect, not the most effective way to manage my own health and kept me from important sources of support. But through continued work with professionals, I eventually learned how to speak about my own mental health in a way that felt safe and professional.
One of the hardest parts of my graduate school career centered around the issue of disclosure. I never felt entirely confident that I was telling people what they needed to know, or that I was safe in disclosing information about my health, mental and otherwise. Some studies estimate that as many as a third of all graduate students are dealing with mental health issues at some point during their graduate studies. As the conversation on campuses about mental health continues to grow, and more and more people call for policies and protections for students and faculty both, but unlike undergraduate students, grad students walk the line between colleague and direct report, often without explicit cues that the roles are switching. So how do you know if you need to disclose a mental health condition to your advisor? Here are my general guidelines, with the explicit acknowledgment that my thoughts are not meant to be prescriptive, but to give you a starting place for thinking through your own relationships.
If your health - mental, physical, emotional - is in jeopardy because of a work deadline or situation, find advocates to help you facilitate the conversation with your advisor. In crisis or acute situations, there are often third parties available on campus to help facilitate these conversations - check your on campus counseling centers, Dean of Students office, or Services for Students with Disabilities office. Just as you might accept documentation for a student in your class of an acute crisis, so too can you offer that same documentation. Even if the conversation is less formal or does not involve documentation, talking to a mental health professional about how to disclose a crisis or acute situation can be a helpful step before talking to your advisor, giving you a script or language to fall back on if the situation is emotional or tense.
You do not need to justify your mental state with details, symptoms, or diagnoses to "prove" the legitimacy of your situation. I often felt the pressure to share more details about a crisis or diagnosis to "prove" that I wasn't suffering from "regular" anxiety and therefore "deserved" the deadline extension or other accommodation. A great rule of thumb is that if you wouldn't share that level of detail for a physical health situation that you are having, you do not need to share it for a mental health situation. If for some reason your advisor or department is pushing for detail that you are not comfortable providing, you can look into obtaining documentation from your health care provider that verifies that you are seeking care without containing details you want to keep private.
Consider building a team beyond your advisor to support your work, especially for long term projects and deadlines. Graduate student advisors are, as we all are, busy people, and very few have the bandwidth available to coach students through the day to day process of producing work. If you only check in with your advisor when major milestones are hit, it might be helpful to build in smaller deadlines with accountability checks to writing groups, writing partners, other committee members, or an outside coach. When the system for enforcing deadlines shrinks to the student-advisor dyad, the temptation to procrastinate, avoid, or ignore work grows, and the relationship can feel adversarial rather than supportive. Having more structure in place to spread out that accountability can help lessen the pressure of the "final" deadline and encourage smaller, more consistent work sessions. You can then keep the day to day challenges of working out of the conversation with your advisor, and seek support from others with less weighted relationships.
Communication (following boundaries that you feel comfortable with) is key. If it becomes clear that a deadline is no longer workable, or that you are in a situation that significantly impacts your work, being in control of the conversation and communication can help to alleviate some of the anxiety of disclosure. Rather than waiting until a deadline or other milestone has been missed to offer an explanation, take the initiative to disclose your situation, and then offer a plan that is workable for you. Email is an amazing tool here - it lets you control the information that you give without the pressure of an in person conversation. Communicating early, and offering solutions that work for you, shows that you are taking responsibility for your work rather than being "caught" when the crisis has already occurred.
Just because you shared details of your mental health in a previous situation does not mean that you are obligated to do so in the future. Being open with other graduate students or peers does not mean that you have to be as open with faculty members. Each situation, and each conversation, is unique. As I was still learning to cope with my anxiety disorder and the pressure of graduate school, I gave more detail than I would later feel comfortable doing. A therapist told me that no one is entitled to details of my mental health just as no one is entitled to details of my physical health. It is my responsibility to take ownership of my own work, my deadlines, and my contributions to the work of the department (teaching, etc) but it is not my responsibility to keep everyone "up to date" on my health unless I felt comfortable doing so. It is appropriate to have different boundaries with different people - openness with some does not obligate you to openness with all.
Mental health challenges is, whether it appears so or not, an increasingly common aspect of graduate school. The more that these conversations happen in safe, productive ways, the more normalized the situation becomes. However, your health, your boundaries, and your needs come first. Hopefully some of these thoughts will help you to formulate your own game plan for how to balance all the aspects of yourself in your professional relationships.