While one day might not solve heavy underlying problems that lead to burnout, a mental health day can provide a much-needed break to pause, regroup, and come back with greater levels of energy and a fresh, less-stressed perspective. Unfortunately, employers are not always supportive of psychological issues that workers may face.
https://www.verywellmind.com/when-and-how-to-take-a-mental-health-day-3144754

