Student mental health in higher education has been worsening for some time, even prior to the pandemic, showing up in various ways that learners struggle in online learning and other modalities. More recent research on health, sleep, and chronic illness as aspects of online learner mental fatigue and academic performance suggests that online learners are experiencing a range of conditions that impact their capacity and their learning. By taking a holistic approach to online learning, we can build systems of care, not just systems of learning. In this piece, we explore the trends in student mental health, implications for online learning, a systemic approach for framing online programs, and why this should be adopted as a "grand challenge" for online learning research and design.