Jean reportedly experienced periods of depression and emotional distress during her late 1930s and early 1940s. The intensity and frequency of these episodes are not fully documented, but they were significant enough to warrant medical attention.

Given that she was studying to become a psychiatrist and was also in distress, Jean sought professional help from colleagues and mentors in the medical field. This reflected her recognition of the importance of mental health care and her willingness to confront her own struggles. It's unclear what specific forms of treatment she received, but it likely involved therapy and possibly medication.

Jean Tatlock died on January 4, 1944, in San Francisco. The circumstances surrounding her death were initially debated. While suicide was determined to be the cause, some conspiracy theories persisted due to her past political affiliations and relationship with Oppenheimer. The coroner's report and available evidence support the conclusion that she took her own life. The autopsy report indicated that she had ingested chloral hydrate (a sedative) and then drowned in her bathtub. She left behind a note expressing despair.