To be clear, sauna in Finland is so universal part of the culture that it's hard to come up with a scenario where a person wouldn't have access. Every home has its own sauna or a shared apartment building sauna; office buildings often have saunas; prisons and military barracks have saunas; elderly homes, ice breakers and even remote archipelago lighthouses have saunas. Every public swimming pool has a sauna, and there are arranged sauna events for homeless people.

During hospital stays you probably do not have the chance due to health and hygiene reasons.

Like the parent posts already said, if you live in Finland you definitely have the means and time to use a sauna.