| Medically speaking a mental illness is no different than a physical illness. Mental illness does not have to be severe just as physical illness does not have to be severe. Sick leave policies typically only require a doctors note/visit if you are absent for multiple days. Taking a single day off for mild mental illness, something like elevated stress levels causing anxiety that interrupts your sleep, seems perfectly consistent with most of the corporate sick leave policies I have read. |
First, "sick days" generally are a policy for handling acute disorders; e.g. last week I didn't have disease X, today I do, and next week I'll be healthy again. You can't "wait out" a mental disease; taking a day or two off may reduce elevated stress levels but that is not the disease, the underlying problems aren't going to be solved when you come back.
The second issue is that many common physical issues are contagious, and there's a strong benefit for the employer and the society for sick people to "quarantine" themselves instead of going to offices and infecting coworkers and customers.
Mental diseases generally all are chronic and not contagious, and so they're similar in workplace (mis)treatment to things like arthritis or diabetes complications; things that don't map neatly to "x days to get cured" but instead need ongoing maintenance and unscheduled downtime forever.